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/*
 * Copyright (c) 2007 Mockito contributors
 * This program is made available under the terms of the MIT License.
 */
package org.mockito;

import org.mockito.exceptions.misusing.PotentialStubbingProblem;
import org.mockito.exceptions.misusing.UnnecessaryStubbingException;
import org.mockito.internal.MockitoCore;
import org.mockito.internal.creation.MockSettingsImpl;
import org.mockito.internal.framework.DefaultMockitoFramework;
import org.mockito.internal.session.DefaultMockitoSessionBuilder;
import org.mockito.internal.verification.VerificationModeFactory;
import org.mockito.invocation.Invocation;
import org.mockito.invocation.InvocationFactory;
import org.mockito.invocation.MockHandler;
import org.mockito.junit.MockitoJUnit;
import org.mockito.junit.MockitoJUnitRunner;
import org.mockito.junit.MockitoJUnitRunner.Strict;
import org.mockito.junit.MockitoRule;
import org.mockito.listeners.VerificationStartedEvent;
import org.mockito.listeners.VerificationStartedListener;
import org.mockito.mock.SerializableMode;
import org.mockito.plugins.MockMaker;
import org.mockito.plugins.MockitoPlugins;
import org.mockito.quality.MockitoHint;
import org.mockito.quality.Strictness;
import org.mockito.session.MockitoSessionBuilder;
import org.mockito.session.MockitoSessionLogger;
import org.mockito.stubbing.Answer;
import org.mockito.stubbing.Answer1;
import org.mockito.stubbing.LenientStubber;
import org.mockito.stubbing.OngoingStubbing;
import org.mockito.stubbing.Stubber;
import org.mockito.stubbing.VoidAnswer1;
import org.mockito.verification.After;
import org.mockito.verification.Timeout;
import org.mockito.verification.VerificationAfterDelay;
import org.mockito.verification.VerificationMode;
import org.mockito.verification.VerificationWithTimeout;

import java.util.function.Consumer;
import java.util.function.Function;

/**
 * 

Mockito logo

* The Mockito library enables mock creation, verification and stubbing. * *

* This javadoc content is also available on the https://site.mockito.org/ web page. * All documentation is kept in javadocs because it guarantees consistency between what's on the web and what's in the source code. * It allows access to documentation straight from the IDE even if you work offline. * It motivates Mockito developers to keep documentation up-to-date with the code that they write, * every day, with every commit. * *

Contents

* * * 0. Migrating to Mockito 2
* 0.1 Mockito Android support
* 0.2 Configuration-free inline mock making
* 1. Let's verify some behaviour!
* 2. How about some stubbing?
* 3. Argument matchers
* 4. Verifying exact number of invocations / at least once / never
* 5. Stubbing void methods with exceptions
* 6. Verification in order
* 7. Making sure interaction(s) never happened on mock
* 8. Finding redundant invocations
* 9. Shorthand for mocks creation - @Mock annotation
* 10. Stubbing consecutive calls (iterator-style stubbing)
* 11. Stubbing with callbacks
* 12. doReturn()|doThrow()|doAnswer()|doNothing()|doCallRealMethod() family of methods
* 13. Spying on real objects
* 14. Changing default return values of un-stubbed invocations (Since 1.7)
* 15. Capturing arguments for further assertions (Since 1.8.0)
* 16. Real partial mocks (Since 1.8.0)
* 17. Resetting mocks (Since 1.8.0)
* 18. Troubleshooting and validating framework usage (Since 1.8.0)
* 19. Aliases for behavior driven development (Since 1.8.0)
* 20. Serializable mocks (Since 1.8.1)
* 21. New annotations: @Captor, @Spy, @InjectMocks (Since 1.8.3)
* 22. Verification with timeout (Since 1.8.5)
* 23. Automatic instantiation of @Spies, @InjectMocks and constructor injection goodness (Since 1.9.0)
* 24. One-liner stubs (Since 1.9.0)
* 25. Verification ignoring stubs (Since 1.9.0)
* 26. Mocking details (Improved in 2.2.x)
* 27. Delegate calls to real instance (Since 1.9.5)
* 28. MockMaker API (Since 1.9.5)
* 29. BDD style verification (Since 1.10.0)
* 30. Spying or mocking abstract classes (Since 1.10.12, further enhanced in 2.7.13 and 2.7.14)
* 31. Mockito mocks can be serialized / deserialized across classloaders (Since 1.10.0)
* 32. Better generic support with deep stubs (Since 1.10.0)
* 33. Mockito JUnit rule (Since 1.10.17)
* 34. Switch on or off plugins (Since 1.10.15)
* 35. Custom verification failure message (Since 2.1.0)
* 36. Java 8 Lambda Matcher Support (Since 2.1.0)
* 37. Java 8 Custom Answer Support (Since 2.1.0)
* 38. Meta data and generic type retention (Since 2.1.0)
* 39. Mocking final types, enums and final methods (Since 2.1.0)
* 40. Improved productivity and cleaner tests with "stricter" Mockito (Since 2.+)
* 41. Advanced public API for framework integrations (Since 2.10.+)
* 42. New API for integrations: listening on verification start events (Since 2.11.+)
* 43. New API for integrations: MockitoSession is usable by testing frameworks (Since 2.15.+)
* 44. Deprecated org.mockito.plugins.InstantiatorProvider as it was leaking internal API. it was replaced by org.mockito.plugins.InstantiatorProvider2 (Since 2.15.4)
* 45. New JUnit Jupiter (JUnit5+) extension
* 46. New Mockito.lenient() and MockSettings.lenient() methods (Since 2.20.0)
* 47. New API for clearing mock state in inline mocking (Since 2.25.0)
* 48. New API for mocking static methods (Since 3.4.0)
* 49. New API for mocking object construction (Since 3.5.0)
* 50. Avoiding code generation when restricting mocks to interfaces (Since 3.12.2)
* 51. New API for marking classes as unmockable (Since 4.1.0)
* 52. New strictness attribute for @Mock annotation and MockSettings.strictness() methods (Since 4.6.0)
* 53. Specifying mock maker for individual mocks (Since 4.8.0)
* 54. Mocking/spying without specifying class (Since 4.9.0)
*
* *

0. Migrating to Mockito 2

* * In order to continue improving Mockito and further improve the unit testing experience, we want you to upgrade to 2.1.0! * Mockito follows semantic versioning and contains breaking changes only on major version upgrades. * In the lifecycle of a library, breaking changes are necessary * to roll out a set of brand new features that alter the existing behavior or even change the API. * For a comprehensive guide on the new release including incompatible changes, * see 'What's new in Mockito 2' wiki page. * We hope that you enjoy Mockito 2! * *

0.1. Mockito Android support

* * With Mockito version 2.6.1 we ship "native" Android support. To enable Android support, add the `mockito-android` library as dependency * to your project. This artifact is published to the same Mockito organization and can be imported for Android as follows: * *

 * repositories {
 *   mavenCentral()
 * }
 * dependencies {
 *   testCompile "org.mockito:mockito-core:+"
 *   androidTestCompile "org.mockito:mockito-android:+"
 * }
 * 
* * You can continue to run the same unit tests on a regular VM by using the `mockito-core` artifact in your "testCompile" scope as shown * above. Be aware that you cannot use the inline mock maker on Android due to limitations in the Android VM. * * If you encounter issues with mocking on Android, please open an issue * on the official issue tracker. * Do provide the version of Android you are working on and dependencies of your project. * *

0.2. Configuration-free inline mock making

* * Starting with version 2.7.6, we offer the 'mockito-inline' artifact that enables inline mock making without configuring * the MockMaker extension file. To use this, add the `mockito-inline` instead of the `mockito-core` artifact as follows: * *

 * repositories {
 *   mavenCentral()
 * }
 * dependencies {
 *   testCompile "org.mockito:mockito-inline:+"
 * }
 * 
* * Be aware that this artifact may be abolished when the inline mock making feature is integrated into the default mock maker. * *

* For more information about inline mock making, see section 39. * *

1. Let's verify some behaviour!

* * The following examples mock a List, because most people are familiar with the interface (such as the * add(), get(), clear() methods).
* In reality, please don't mock the List class. Use a real instance instead. * *

 * //Let's import Mockito statically so that the code looks clearer
 * import static org.mockito.Mockito.*;
 *
 * //mock creation
 * List mockedList = mock(List.class);
 *
 * //using mock object
 * mockedList.add("one");
 * mockedList.clear();
 *
 * //verification
 * verify(mockedList).add("one");
 * verify(mockedList).clear();
 * 
* *

* Once created, a mock will remember all interactions. Then you can selectively * verify whatever interactions you are interested in. *

* * * *

2. How about some stubbing?

* *

 * //You can mock concrete classes, not just interfaces
 * LinkedList mockedList = mock(LinkedList.class);
 *
 * //stubbing
 * when(mockedList.get(0)).thenReturn("first");
 * when(mockedList.get(1)).thenThrow(new RuntimeException());
 *
 * //following prints "first"
 * System.out.println(mockedList.get(0));
 *
 * //following throws runtime exception
 * System.out.println(mockedList.get(1));
 *
 * //following prints "null" because get(999) was not stubbed
 * System.out.println(mockedList.get(999));
 *
 * //Although it is possible to verify a stubbed invocation, usually it's just redundant
 * //If your code cares what get(0) returns, then something else breaks (often even before verify() gets executed).
 * //If your code doesn't care what get(0) returns, then it should not be stubbed.
 * verify(mockedList).get(0);
 * 
* *
    *
  • By default, for all methods that return a value, a mock will return either null, * a primitive/primitive wrapper value, or an empty collection, as appropriate. * For example 0 for an int/Integer and false for a boolean/Boolean.
  • * *
  • Stubbing can be overridden: for example common stubbing can go to * fixture setup but the test methods can override it. * Please note that overriding stubbing is a potential code smell that points out too much stubbing
  • * *
  • Once stubbed, the method will always return a stubbed value, regardless * of how many times it is called.
  • * *
  • Last stubbing is more important - when you stubbed the same method with * the same arguments many times. * Other words: the order of stubbing matters but it is only meaningful rarely, * e.g. when stubbing exactly the same method calls or sometimes when argument matchers are used, etc.
  • * *
* * * *

3. Argument matchers

* * Mockito verifies argument values in natural java style: by using an equals() method. * Sometimes, when extra flexibility is required then you might use argument matchers: * *

 * //stubbing using built-in anyInt() argument matcher
 * when(mockedList.get(anyInt())).thenReturn("element");
 *
 * //stubbing using custom matcher (let's say isValid() returns your own matcher implementation):
 * when(mockedList.contains(argThat(isValid()))).thenReturn(true);
 *
 * //following prints "element"
 * System.out.println(mockedList.get(999));
 *
 * //you can also verify using an argument matcher
 * verify(mockedList).get(anyInt());
 *
 * //argument matchers can also be written as Java 8 Lambdas
 * verify(mockedList).add(argThat(someString -> someString.length() > 5));
 *
 * 
* *

* Argument matchers allow flexible verification or stubbing. * {@link ArgumentMatchers Click here} {@link org.mockito.hamcrest.MockitoHamcrest or here} to see more built-in matchers * and examples of custom argument matchers / hamcrest matchers. *

* For information solely on custom argument matchers check out javadoc for {@link ArgumentMatcher} class. *

* Be reasonable with using complicated argument matching. * The natural matching style using equals() with occasional anyX() matchers tend to give clean and simple tests. * Sometimes it's just better to refactor the code to allow equals() matching or even implement equals() method to help out with testing. *

* Also, read section 15 or javadoc for {@link ArgumentCaptor} class. * {@link ArgumentCaptor} is a special implementation of an argument matcher that captures argument values for further assertions. *

* Warning on argument matchers: *

* If you are using argument matchers, all arguments have to be provided * by matchers. *

* The following example shows verification but the same applies to stubbing: * *


 *   verify(mock).someMethod(anyInt(), anyString(), eq("third argument"));
 *   //above is correct - eq() is also an argument matcher
 *
 *   verify(mock).someMethod(anyInt(), anyString(), "third argument");
 *   //above is incorrect - exception will be thrown because third argument is given without an argument matcher.
 * 
* *

* Matcher methods like any(), eq() do not return matchers. * Internally, they record a matcher on a stack and return a dummy value (usually null). * This implementation is due to static type safety imposed by the java compiler. * The consequence is that you cannot use any(), eq() methods outside of verified/stubbed method. * * * * *

4. Verifying exact number of invocations / * at least x / never

* *

 * //using mock
 * mockedList.add("once");
 *
 * mockedList.add("twice");
 * mockedList.add("twice");
 *
 * mockedList.add("three times");
 * mockedList.add("three times");
 * mockedList.add("three times");
 *
 * //following two verifications work exactly the same - times(1) is used by default
 * verify(mockedList).add("once");
 * verify(mockedList, times(1)).add("once");
 *
 * //exact number of invocations verification
 * verify(mockedList, times(2)).add("twice");
 * verify(mockedList, times(3)).add("three times");
 *
 * //verification using never(). never() is an alias to times(0)
 * verify(mockedList, never()).add("never happened");
 *
 * //verification using atLeast()/atMost()
 * verify(mockedList, atMostOnce()).add("once");
 * verify(mockedList, atLeastOnce()).add("three times");
 * verify(mockedList, atLeast(2)).add("three times");
 * verify(mockedList, atMost(5)).add("three times");
 *
 * 
* *

* times(1) is the default. Therefore using times(1) explicitly can be * omitted. * * * * *

5. Stubbing void methods with exceptions

* *

 *   doThrow(new RuntimeException()).when(mockedList).clear();
 *
 *   //following throws RuntimeException:
 *   mockedList.clear();
 * 
* * Read more about doThrow()|doAnswer() family of methods in section 12. *

* *

6. Verification in order

* *

 * // A. Single mock whose methods must be invoked in a particular order
 * List singleMock = mock(List.class);
 *
 * //using a single mock
 * singleMock.add("was added first");
 * singleMock.add("was added second");
 *
 * //create an inOrder verifier for a single mock
 * InOrder inOrder = inOrder(singleMock);
 *
 * //following will make sure that add is first called with "was added first", then with "was added second"
 * inOrder.verify(singleMock).add("was added first");
 * inOrder.verify(singleMock).add("was added second");
 *
 * // B. Multiple mocks that must be used in a particular order
 * List firstMock = mock(List.class);
 * List secondMock = mock(List.class);
 *
 * //using mocks
 * firstMock.add("was called first");
 * secondMock.add("was called second");
 *
 * //create inOrder object passing any mocks that need to be verified in order
 * InOrder inOrder = inOrder(firstMock, secondMock);
 *
 * //following will make sure that firstMock was called before secondMock
 * inOrder.verify(firstMock).add("was called first");
 * inOrder.verify(secondMock).add("was called second");
 *
 * // Oh, and A + B can be mixed together at will
 * 
* * Verification in order is flexible - you don't have to verify all * interactions one-by-one but only those that you are interested in * testing in order. *

* Also, you can create an InOrder object passing only the mocks that are relevant for * in-order verification. * * * * *

7. Making sure interaction(s) never happened on mock

* *

 * //using mocks - only mockOne is interacted
 * mockOne.add("one");
 *
 * //ordinary verification
 * verify(mockOne).add("one");
 *
 * //verify that method was never called on a mock
 * verify(mockOne, never()).add("two");
 *
 * 
* * * * *

8. Finding redundant invocations

* *

 * //using mocks
 * mockedList.add("one");
 * mockedList.add("two");
 *
 * verify(mockedList).add("one");
 *
 * //following verification will fail
 * verifyNoMoreInteractions(mockedList);
 * 
* * A word of warning: * Some users who did a lot of classic, expect-run-verify mocking tend to use verifyNoMoreInteractions() very often, even in every test method. * verifyNoMoreInteractions() is not recommended to use in every test method. * verifyNoMoreInteractions() is a handy assertion from the interaction testing toolkit. Use it only when it's relevant. * Abusing it leads to overspecified, less maintainable tests. * *

* See also {@link Mockito#never()} - it is more explicit and * communicates the intent well. *

* * * * *

9. Shorthand for mocks creation - @Mock annotation

* *
    *
  • Minimizes repetitive mock creation code.
  • *
  • Makes the test class more readable.
  • *
  • Makes the verification error easier to read because the field name * is used to identify the mock.
  • *
* *

 *   public class ArticleManagerTest {
 *
 *       @Mock private ArticleCalculator calculator;
 *       @Mock private ArticleDatabase database;
 *       @Mock private UserProvider userProvider;
 *
 *       private ArticleManager manager;
 *
 *       @org.junit.jupiter.api.Test
 *       void testSomethingInJunit5(@Mock ArticleDatabase database) {
 * 
* * Important! This needs to be somewhere in the base class or a test * runner: * *

 * MockitoAnnotations.openMocks(testClass);
 * 
* * You can use built-in runner: {@link MockitoJUnitRunner} or a rule: {@link MockitoRule}. * For JUnit5 tests, refer to the JUnit5 extension described in section 45. *

* Read more here: {@link MockitoAnnotations} * * * * *

10. Stubbing consecutive calls (iterator-style stubbing)

* * Sometimes we need to stub with different return value/exception for the same * method call. Typical use case could be mocking iterators. * Original version of Mockito did not have this feature to promote simple mocking. * For example, instead of iterators one could use {@link Iterable} or simply * collections. Those offer natural ways of stubbing (e.g. using real * collections). In rare scenarios stubbing consecutive calls could be useful, * though: *

* *


 * when(mock.someMethod("some arg"))
 *   .thenThrow(new RuntimeException())
 *   .thenReturn("foo");
 *
 * //First call: throws runtime exception:
 * mock.someMethod("some arg");
 *
 * //Second call: prints "foo"
 * System.out.println(mock.someMethod("some arg"));
 *
 * //Any consecutive call: prints "foo" as well (last stubbing wins).
 * System.out.println(mock.someMethod("some arg"));
 * 
* * Alternative, shorter version of consecutive stubbing: * *

 * when(mock.someMethod("some arg"))
 *   .thenReturn("one", "two", "three");
 * 
* * Warning : if instead of chaining {@code .thenReturn()} calls, multiple stubbing with the same matchers or arguments * is used, then each stubbing will override the previous one: * *

 * //All mock.someMethod("some arg") calls will return "two"
 * when(mock.someMethod("some arg"))
 *   .thenReturn("one")
 * when(mock.someMethod("some arg"))
 *   .thenReturn("two")
 * 
* * * *

11. Stubbing with callbacks

* * Allows stubbing with generic {@link Answer} interface. *

* Yet another controversial feature which was not included in Mockito * originally. We recommend simply stubbing with thenReturn() or * thenThrow(), which should be enough to test/test-drive * any clean and simple code. However, if you do have a need to stub with the generic Answer interface, here is an example: * *


 * when(mock.someMethod(anyString())).thenAnswer(
 *     new Answer() {
 *         public Object answer(InvocationOnMock invocation) {
 *             Object[] args = invocation.getArguments();
 *             Object mock = invocation.getMock();
 *             return "called with arguments: " + Arrays.toString(args);
 *         }
 * });
 *
 * //Following prints "called with arguments: [foo]"
 * System.out.println(mock.someMethod("foo"));
 * 
* * * * *

12. doReturn()|doThrow()| * doAnswer()|doNothing()|doCallRealMethod() family of methods

* * Stubbing void methods requires a different approach from {@link Mockito#when(Object)} because the compiler does not * like void methods inside brackets... *

* Use doThrow() when you want to stub a void method with an exception: *


 *   doThrow(new RuntimeException()).when(mockedList).clear();
 *
 *   //following throws RuntimeException:
 *   mockedList.clear();
 * 
*

* *

* You can use doThrow(), doAnswer(), doNothing(), doReturn() * and doCallRealMethod() in place of the corresponding call with when(), for any method. * It is necessary when you *

    *
  • stub void methods
  • *
  • stub methods on spy objects (see below)
  • *
  • stub the same method more than once, to change the behaviour of a mock in the middle of a test.
  • *
* but you may prefer to use these methods in place of the alternative with when(), for all of your stubbing calls. *

* Read more about these methods: *

* {@link Mockito#doReturn(Object)} *

* {@link Mockito#doThrow(Throwable...)} *

* {@link Mockito#doThrow(Class)} *

* {@link Mockito#doAnswer(Answer)} *

* {@link Mockito#doNothing()} *

* {@link Mockito#doCallRealMethod()} * * * * *

13. Spying on real objects

* * You can create spies of real objects. When you use the spy then the real methods are called * (unless a method was stubbed). *

* Real spies should be used carefully and occasionally, for example when dealing with legacy code. * *

* Spying on real objects can be associated with "partial mocking" concept. * Before the release 1.8, Mockito spies were not real partial mocks. * The reason was we thought partial mock is a code smell. * At some point we found legitimate use cases for partial mocks * (3rd party interfaces, interim refactoring of legacy code). *

* *


 *   List list = new LinkedList();
 *   List spy = spy(list);
 *
 *   //optionally, you can stub out some methods:
 *   when(spy.size()).thenReturn(100);
 *
 *   //using the spy calls *real* methods
 *   spy.add("one");
 *   spy.add("two");
 *
 *   //prints "one" - the first element of a list
 *   System.out.println(spy.get(0));
 *
 *   //size() method was stubbed - 100 is printed
 *   System.out.println(spy.size());
 *
 *   //optionally, you can verify
 *   verify(spy).add("one");
 *   verify(spy).add("two");
 * 
* *

Important gotcha on spying real objects!

*
    *
  1. Sometimes it's impossible or impractical to use {@link Mockito#when(Object)} for stubbing spies. * Therefore when using spies please consider doReturn|Answer|Throw() family of * methods for stubbing. Example: * *
    
     *   List list = new LinkedList();
     *   List spy = spy(list);
     *
     *   //Impossible: real method is called so spy.get(0) throws IndexOutOfBoundsException (the list is yet empty)
     *   when(spy.get(0)).thenReturn("foo");
     *
     *   //You have to use doReturn() for stubbing
     *   doReturn("foo").when(spy).get(0);
     * 
    *
  2. * *
  3. Mockito *does not* delegate calls to the passed real instance, instead it actually creates a copy of it. * So if you keep the real instance and interact with it, don't expect the spied to be aware of those interaction * and their effect on real instance state. * The corollary is that when an *un-stubbed* method is called *on the spy* but *not on the real instance*, * you won't see any effects on the real instance. *
  4. * *
  5. Watch out for final methods. * Mockito doesn't mock final methods so the bottom line is: when you spy on real objects + you try to stub a final method = trouble. * Also you won't be able to verify those method as well. *
  6. *
* * * * *

14. Changing default return values of un-stubbed invocations (Since 1.7)

* * You can create a mock with specified strategy for its return values. * It's quite an advanced feature and typically you don't need it to write decent tests. * However, it can be helpful for working with legacy systems. *

* It is the default answer so it will be used only when you don't stub the method call. * *


 *   Foo mock = mock(Foo.class, Mockito.RETURNS_SMART_NULLS);
 *   Foo mockTwo = mock(Foo.class, new YourOwnAnswer());
 * 
* *

* Read more about this interesting implementation of Answer: {@link Mockito#RETURNS_SMART_NULLS} * * * * *

15. Capturing arguments for further assertions (Since 1.8.0)

* * Mockito verifies argument values in natural java style: by using an equals() method. * This is also the recommended way of matching arguments because it makes tests clean and simple. * In some situations though, it is helpful to assert on certain arguments after the actual verification. * For example: *

 *   ArgumentCaptor<Person> argument = ArgumentCaptor.forClass(Person.class);
 *   verify(mock).doSomething(argument.capture());
 *   assertEquals("John", argument.getValue().getName());
 * 
* * Warning: it is recommended to use ArgumentCaptor with verification but not with stubbing. * Using ArgumentCaptor with stubbing may decrease test readability because captor is created outside of assert (aka verify or 'then') block. * Also it may reduce defect localization because if stubbed method was not called then no argument is captured. *

* In a way ArgumentCaptor is related to custom argument matchers (see javadoc for {@link ArgumentMatcher} class). * Both techniques can be used for making sure certain arguments were passed to mocks. * However, ArgumentCaptor may be a better fit if: *

    *
  • custom argument matcher is not likely to be reused
  • *
  • you just need it to assert on argument values to complete verification
  • *
* Custom argument matchers via {@link ArgumentMatcher} are usually better for stubbing. * * * * *

16. Real partial mocks (Since 1.8.0)

* * Finally, after many internal debates and discussions on the mailing list, partial mock support was added to Mockito. * Previously we considered partial mocks as code smells. However, we found a legitimate use case for partial mocks. *

* Before release 1.8 spy() was not producing real partial mocks and it was confusing for some users. * Read more about spying: here or in javadoc for {@link Mockito#spy(Object)} method. *

*


 *    //you can create partial mock with spy() method:
 *    List list = spy(new LinkedList());
 *
 *    //you can enable partial mock capabilities selectively on mocks:
 *    Foo mock = mock(Foo.class);
 *    //Be sure the real implementation is 'safe'.
 *    //If real implementation throws exceptions or depends on specific state of the object then you're in trouble.
 *    when(mock.someMethod()).thenCallRealMethod();
 *  
* * As usual you are going to read the partial mock warning: * Object oriented programming is more less tackling complexity by dividing the complexity into separate, specific, SRPy objects. * How does partial mock fit into this paradigm? Well, it just doesn't... * Partial mock usually means that the complexity has been moved to a different method on the same object. * In most cases, this is not the way you want to design your application. *

* However, there are rare cases when partial mocks come handy: * dealing with code you cannot change easily (3rd party interfaces, interim refactoring of legacy code etc.) * However, I wouldn't use partial mocks for new, test-driven and well-designed code. * * * * *

17. Resetting mocks (Since 1.8.0)

* * Smart Mockito users hardly use this feature because they know it could be a sign of poor tests. * Normally, you don't need to reset your mocks, just create new mocks for each test method. *

* Instead of reset() please consider writing simple, small and focused test methods over lengthy, over-specified tests. * First potential code smell is reset() in the middle of the test method. This probably means you're testing too much. * Follow the whisper of your test methods: "Please keep us small and focused on single behavior". * There are several threads about it on mockito mailing list. *

* The only reason we added reset() method is to * make it possible to work with container-injected mocks. * For more information see FAQ (here). *

* Don't harm yourself. reset() in the middle of the test method is a code smell (you're probably testing too much). *


 *   List mock = mock(List.class);
 *   when(mock.size()).thenReturn(10);
 *   mock.add(1);
 *
 *   reset(mock);
 *   //at this point the mock forgot any interactions and stubbing
 * 
* * * * *

18. Troubleshooting and validating framework usage (Since 1.8.0)

* * First of all, in case of any trouble, I encourage you to read the Mockito FAQ: * https://github.com/mockito/mockito/wiki/FAQ *

* In case of questions you may also post to mockito mailing list: * https://groups.google.com/group/mockito *

* Next, you should know that Mockito validates if you use it correctly all the time. * However, there's a gotcha so please read the javadoc for {@link Mockito#validateMockitoUsage()} * * * * *

19. Aliases for behavior driven development (Since 1.8.0)

* * Behavior Driven Development style of writing tests uses //given //when //then comments as fundamental parts of your test methods. * This is exactly how we write our tests and we warmly encourage you to do so! *

* Start learning about BDD here: https://en.wikipedia.org/wiki/Behavior-driven_development *

* The problem is that current stubbing api with canonical role of when word does not integrate nicely with //given //when //then comments. * It's because stubbing belongs to given component of the test and not to the when component of the test. * Hence {@link BDDMockito} class introduces an alias so that you stub method calls with {@link BDDMockito#given(Object)} method. * Now it really nicely integrates with the given component of a BDD style test! *

* Here is how the test might look like: *


 * import static org.mockito.BDDMockito.*;
 *
 * Seller seller = mock(Seller.class);
 * Shop shop = new Shop(seller);
 *
 * public void shouldBuyBread() throws Exception {
 *   //given
 *   given(seller.askForBread()).willReturn(new Bread());
 *
 *   //when
 *   Goods goods = shop.buyBread();
 *
 *   //then
 *   assertThat(goods, containBread());
 * }
 * 
* * * * *

20. Serializable mocks (Since 1.8.1)

* * Mocks can be made serializable. With this feature you can use a mock in a place that requires dependencies to be serializable. *

* WARNING: This should be rarely used in unit testing. *

* The behaviour was implemented for a specific use case of a BDD spec that had an unreliable external dependency. This * was in a web environment and the objects from the external dependency were being serialized to pass between layers. *

* To create serializable mock use {@link MockSettings#serializable()}: *


 *   List serializableMock = mock(List.class, withSettings().serializable());
 * 
*

* The mock can be serialized assuming all the normal * serialization requirements are met by the class. *

* Making a real object spy serializable is a bit more effort as the spy(...) method does not have an overloaded version * which accepts MockSettings. No worries, you will hardly ever use it. * *


 * List<Object> list = new ArrayList<Object>();
 * List<Object> spy = mock(ArrayList.class, withSettings()
 *                 .spiedInstance(list)
 *                 .defaultAnswer(CALLS_REAL_METHODS)
 *                 .serializable());
 * 
* * * * *

21. New annotations: @Captor, * @Spy, * @InjectMocks (Since 1.8.3)

* *

* Release 1.8.3 brings new annotations that may be helpful on occasion: * *

    *
  • @{@link Captor} simplifies creation of {@link ArgumentCaptor} * - useful when the argument to capture is a nasty generic class and you want to avoid compiler warnings *
  • @{@link Spy} - you can use it instead {@link Mockito#spy(Object)}. *
  • @{@link InjectMocks} - injects mock or spy fields into tested object automatically. *
* *

* Note that @{@link InjectMocks} can also be used in combination with the @{@link Spy} annotation, it means * that Mockito will inject mocks into the partial mock under test. This complexity is another good reason why you * should only use partial mocks as a last resort. See point 16 about partial mocks. * *

* All new annotations are *only* processed on {@link MockitoAnnotations#openMocks(Object)}. * Just like for @{@link Mock} annotation you can use the built-in runner: {@link MockitoJUnitRunner} or rule: * {@link MockitoRule}. *

* * * * *

22. Verification with timeout (Since 1.8.5)

*

* Allows verifying with timeout. It causes a verify to wait for a specified period of time for a desired * interaction rather than fails immediately if had not already happened. May be useful for testing in concurrent * conditions. *

* This feature should be used rarely - figure out a better way of testing your multi-threaded system. *

* Not yet implemented to work with InOrder verification. *

* Examples: *

*


 *   //passes when someMethod() is called no later than within 100 ms
 *   //exits immediately when verification is satisfied (e.g. may not wait full 100 ms)
 *   verify(mock, timeout(100)).someMethod();
 *   //above is an alias to:
 *   verify(mock, timeout(100).times(1)).someMethod();
 *
 *   //passes as soon as someMethod() has been called 2 times under 100 ms
 *   verify(mock, timeout(100).times(2)).someMethod();
 *
 *   //equivalent: this also passes as soon as someMethod() has been called 2 times under 100 ms
 *   verify(mock, timeout(100).atLeast(2)).someMethod();
 * 
* * * * *

23. Automatic instantiation of @Spies, * @InjectMocks and constructor injection goodness (Since 1.9.0)

* *

* Mockito will now try to instantiate @{@link Spy} and will instantiate @{@link InjectMocks} fields * using constructor injection, setter injection, or field injection. *

* To take advantage of this feature you need to use {@link MockitoAnnotations#openMocks(Object)}, {@link MockitoJUnitRunner} * or {@link MockitoRule}. *

* Read more about available tricks and the rules of injection in the javadoc for {@link InjectMocks} *


 * //instead:
 * @Spy BeerDrinker drinker = new BeerDrinker();
 * //you can write:
 * @Spy BeerDrinker drinker;
 *
 * //same applies to @InjectMocks annotation:
 * @InjectMocks LocalPub;
 * 
* * * * *

24. One-liner stubs (Since 1.9.0)

*

* Mockito will now allow you to create mocks when stubbing. * Basically, it allows to create a stub in one line of code. * This can be helpful to keep test code clean. * For example, some boring stub can be created and stubbed at field initialization in a test: *


 * public class CarTest {
 *   Car boringStubbedCar = when(mock(Car.class).shiftGear()).thenThrow(EngineNotStarted.class).getMock();
 *
 *   @Test public void should... {}
 * 
* * * * *

25. Verification ignoring stubs (Since 1.9.0)

*

* Mockito will now allow to ignore stubbing for the sake of verification. * Sometimes useful when coupled with verifyNoMoreInteractions() or verification inOrder(). * Helps avoiding redundant verification of stubbed calls - typically we're not interested in verifying stubs. *

* Warning, ignoreStubs() might lead to overuse of verifyNoMoreInteractions(ignoreStubs(...)); * Bear in mind that Mockito does not recommend bombarding every test with verifyNoMoreInteractions() * for the reasons outlined in javadoc for {@link Mockito#verifyNoMoreInteractions(Object...)} *

Some examples: *


 * verify(mock).foo();
 * verify(mockTwo).bar();
 *
 * //ignores all stubbed methods:
 * verifyNoMoreInteractions(ignoreStubs(mock, mockTwo));
 *
 * //creates InOrder that will ignore stubbed
 * InOrder inOrder = inOrder(ignoreStubs(mock, mockTwo));
 * inOrder.verify(mock).foo();
 * inOrder.verify(mockTwo).bar();
 * inOrder.verifyNoMoreInteractions();
 * 
*

* Advanced examples and more details can be found in javadoc for {@link Mockito#ignoreStubs(Object...)} * * * * *

26. Mocking details (Improved in 2.2.x)

*

* * Mockito offers API to inspect the details of a mock object. * This API is useful for advanced users and mocking framework integrators. * *


 *   //To identify whether a particular object is a mock or a spy:
 *   Mockito.mockingDetails(someObject).isMock();
 *   Mockito.mockingDetails(someObject).isSpy();
 *
 *   //Getting details like type to mock or default answer:
 *   MockingDetails details = mockingDetails(mock);
 *   details.getMockCreationSettings().getTypeToMock();
 *   details.getMockCreationSettings().getDefaultAnswer();
 *
 *   //Getting invocations and stubbings of the mock:
 *   MockingDetails details = mockingDetails(mock);
 *   details.getInvocations();
 *   details.getStubbings();
 *
 *   //Printing all interactions (including stubbing, unused stubs)
 *   System.out.println(mockingDetails(mock).printInvocations());
 * 
* * For more information see javadoc for {@link MockingDetails}. * *

27. Delegate calls to real instance (Since 1.9.5)

* *

Useful for spies or partial mocks of objects that are difficult to mock or spy using the usual spy API. * Since Mockito 1.10.11, the delegate may or may not be of the same type as the mock. * If the type is different, a matching method needs to be found on delegate type otherwise an exception is thrown. * * Possible use cases for this feature: *

    *
  • Final classes but with an interface
  • *
  • Already custom proxied object
  • *
  • Special objects with a finalize method, i.e. to avoid executing it 2 times
  • *
* *

The difference with the regular spy: *

    *
  • * The regular spy ({@link #spy(Object)}) contains all state from the spied instance * and the methods are invoked on the spy. The spied instance is only used at mock creation to copy the state from. * If you call a method on a regular spy and it internally calls other methods on this spy, those calls are remembered * for verifications, and they can be effectively stubbed. *
  • *
  • * The mock that delegates simply delegates all methods to the delegate. * The delegate is used all the time as methods are delegated onto it. * If you call a method on a mock that delegates and it internally calls other methods on this mock, * those calls are not remembered for verifications, stubbing does not have effect on them, too. * Mock that delegates is less powerful than the regular spy but it is useful when the regular spy cannot be created. *
  • *
* *

* See more information in docs for {@link AdditionalAnswers#delegatesTo(Object)}. * * * * *

28. MockMaker API (Since 1.9.5)

*

Driven by requirements and patches from Google Android guys Mockito now offers an extension point * that allows replacing the proxy generation engine. By default, Mockito uses Byte Buddy * to create dynamic proxies. *

The extension point is for advanced users that want to extend Mockito. For example, it is now possible * to use Mockito for Android testing with a help of dexmaker. *

For more details, motivations and examples please refer to * the docs for {@link org.mockito.plugins.MockMaker}. * * * * *

29. BDD style verification (Since 1.10.0)

* * Enables Behavior Driven Development (BDD) style verification by starting verification with the BDD then keyword. * *

 * given(dog.bark()).willReturn(2);
 *
 * // when
 * ...
 *
 * then(person).should(times(2)).ride(bike);
 * 
* * For more information and an example see {@link BDDMockito#then(Object)} * * * * *

30. Spying or mocking abstract classes (Since 1.10.12, further enhanced in 2.7.13 and 2.7.14)

* * It is now possible to conveniently spy on abstract classes. Note that overusing spies hints at code design smells (see {@link #spy(Object)}). *

* Previously, spying was only possible on instances of objects. * New API makes it possible to use constructor when creating an instance of the mock. * This is particularly useful for mocking abstract classes because the user is no longer required to provide an instance of the abstract class. * At the moment, only parameter-less constructor is supported, let us know if it is not enough. * *


 * //convenience API, new overloaded spy() method:
 * SomeAbstract spy = spy(SomeAbstract.class);
 *
 * //Mocking abstract methods, spying default methods of an interface (only available since 2.7.13)
 * Function<Foo, Bar> function = spy(Function.class);
 *
 * //Robust API, via settings builder:
 * OtherAbstract spy = mock(OtherAbstract.class, withSettings()
 *    .useConstructor().defaultAnswer(CALLS_REAL_METHODS));
 *
 * //Mocking an abstract class with constructor arguments (only available since 2.7.14)
 * SomeAbstract spy = mock(SomeAbstract.class, withSettings()
 *   .useConstructor("arg1", 123).defaultAnswer(CALLS_REAL_METHODS));
 *
 * //Mocking a non-static inner abstract class:
 * InnerAbstract spy = mock(InnerAbstract.class, withSettings()
 *    .useConstructor().outerInstance(outerInstance).defaultAnswer(CALLS_REAL_METHODS));
 * 
* * For more information please see {@link MockSettings#useConstructor(Object...)}. * * * * *

31. Mockito mocks can be serialized / deserialized across classloaders (Since 1.10.0)

* * Mockito introduces serialization across classloader. * * Like with any other form of serialization, all types in the mock hierarchy have to serializable, including answers. * As this serialization mode require considerably more work, this is an opt-in setting. * *

 * // use regular serialization
 * mock(Book.class, withSettings().serializable());
 *
 * // use serialization across classloaders
 * mock(Book.class, withSettings().serializable(ACROSS_CLASSLOADERS));
 * 
* * For more details see {@link MockSettings#serializable(SerializableMode)}. * * * * *

32. Better generic support with deep stubs (Since 1.10.0)

* * Deep stubbing has been improved to find generic information if available in the class. * That means that classes like this can be used without having to mock the behavior. * *

 * class Lines extends List<Line> {
 *     // ...
 * }
 *
 * lines = mock(Lines.class, RETURNS_DEEP_STUBS);
 *
 * // Now Mockito understand this is not an Object but a Line
 * Line line = lines.iterator().next();
 * 
* * Please note that in most scenarios a mock returning a mock is wrong. * * * * *

33. Mockito JUnit rule (Since 1.10.17)

* * Mockito now offers a JUnit rule. Until now in JUnit there were two ways to initialize fields annotated by Mockito annotations * such as @{@link Mock}, @{@link Spy}, @{@link InjectMocks}, etc. * *
    *
  • Annotating the JUnit test class with a @{@link org.junit.runner.RunWith}({@link MockitoJUnitRunner}.class)
  • *
  • Invoking {@link MockitoAnnotations#openMocks(Object)} in the @{@link org.junit.Before} method
  • *
* * Now you can choose to use a rule : * *

 * @RunWith(YetAnotherRunner.class)
 * public class TheTest {
 *     @Rule public MockitoRule mockito = MockitoJUnit.rule();
 *     // ...
 * }
 * 
* * For more information see {@link MockitoJUnit#rule()}. * * * * *

34. Switch on or off plugins (Since 1.10.15)

* * An incubating feature made it's way in mockito that will allow to toggle a mockito-plugin. * * More information here {@link org.mockito.plugins.PluginSwitch}. * * *

35. Custom verification failure message (Since 2.1.0)

*

* Allows specifying a custom message to be printed if verification fails. *

* Examples: *

*


 *
 * // will print a custom message on verification failure
 * verify(mock, description("This will print on failure")).someMethod();
 *
 * // will work with any verification mode
 * verify(mock, times(2).description("someMethod should be called twice")).someMethod();
 * 
* *

36. Java 8 Lambda Matcher Support (Since 2.1.0)

*

* You can use Java 8 lambda expressions with {@link ArgumentMatcher} to reduce the dependency on {@link ArgumentCaptor}. * If you need to verify that the input to a function call on a mock was correct, then you would normally * use the {@link ArgumentCaptor} to find the operands used and then do subsequent assertions on them. While * for complex examples this can be useful, it's also long-winded.

* Writing a lambda to express the match is quite easy. The argument to your function, when used in conjunction * with argThat, will be passed to the ArgumentMatcher as a strongly typed object, so it is possible * to do anything with it. *

* Examples: *

*


 *
 * // verify a list only had strings of a certain length added to it
 * // note - this will only compile under Java 8
 * verify(list, times(2)).add(argThat(string -> string.length() < 5));
 *
 * // Java 7 equivalent - not as neat
 * verify(list, times(2)).add(argThat(new ArgumentMatcher<String>(){
 *     public boolean matches(String arg) {
 *         return arg.length() < 5;
 *     }
 * }));
 *
 * // more complex Java 8 example - where you can specify complex verification behaviour functionally
 * verify(target, times(1)).receiveComplexObject(argThat(obj -> obj.getSubObject().get(0).equals("expected")));
 *
 * // this can also be used when defining the behaviour of a mock under different inputs
 * // in this case if the input list was fewer than 3 items the mock returns null
 * when(mock.someMethod(argThat(list -> list.size()<3))).thenReturn(null);
 * 
* *

37. Java 8 Custom Answer Support (Since 2.1.0)

*

* As the {@link Answer} interface has just one method it is already possible to implement it in Java 8 using * a lambda expression for very simple situations. The more you need to use the parameters of the method call, * the more you need to typecast the arguments from {@link org.mockito.invocation.InvocationOnMock}. * *

* Examples: *

*


 * // answer by returning 12 every time
 * doAnswer(invocation -> 12).when(mock).doSomething();
 *
 * // answer by using one of the parameters - converting into the right
 * // type as your go - in this case, returning the length of the second string parameter
 * // as the answer. This gets long-winded quickly, with casting of parameters.
 * doAnswer(invocation -> ((String)invocation.getArgument(1)).length())
 *     .when(mock).doSomething(anyString(), anyString(), anyString());
 * 
* * For convenience it is possible to write custom answers/actions, which use the parameters to the method call, * as Java 8 lambdas. Even in Java 7 and lower these custom answers based on a typed interface can reduce boilerplate. * In particular, this approach will make it easier to test functions which use callbacks. * * The methods {@link AdditionalAnswers#answer(Answer1)}} and {@link AdditionalAnswers#answerVoid(VoidAnswer1)} * can be used to create the answer. They rely on the related answer interfaces in org.mockito.stubbing that * support answers up to 5 parameters. * *

* Examples: *

*


 *
 * // Example interface to be mocked has a function like:
 * void execute(String operand, Callback callback);
 *
 * // the example callback has a function and the class under test
 * // will depend on the callback being invoked
 * void receive(String item);
 *
 * // Java 8 - style 1
 * doAnswer(AdditionalAnswers.<String,Callback>answerVoid((operand, callback) -> callback.receive("dummy")))
 *     .when(mock).execute(anyString(), any(Callback.class));
 *
 * // Java 8 - style 2 - assuming static import of AdditionalAnswers
 * doAnswer(answerVoid((String operand, Callback callback) -> callback.receive("dummy")))
 *     .when(mock).execute(anyString(), any(Callback.class));
 *
 * // Java 8 - style 3 - where mocking function to is a static member of test class
 * private static void dummyCallbackImpl(String operation, Callback callback) {
 *     callback.receive("dummy");
 * }
 *
 * doAnswer(answerVoid(TestClass::dummyCallbackImpl))
 *     .when(mock).execute(anyString(), any(Callback.class));
 *
 * // Java 7
 * doAnswer(answerVoid(new VoidAnswer2<String, Callback>() {
 *     public void answer(String operation, Callback callback) {
 *         callback.receive("dummy");
 *     }})).when(mock).execute(anyString(), any(Callback.class));
 *
 * // returning a value is possible with the answer() function
 * // and the non-void version of the functional interfaces
 * // so if the mock interface had a method like
 * boolean isSameString(String input1, String input2);
 *
 * // this could be mocked
 * // Java 8
 * doAnswer(AdditionalAnswers.<Boolean,String,String>answer((input1, input2) -> input1.equals(input2)))
 *     .when(mock).execute(anyString(), anyString());
 *
 * // Java 7
 * doAnswer(answer(new Answer2<String, String, String>() {
 *     public String answer(String input1, String input2) {
 *         return input1 + input2;
 *     }})).when(mock).execute(anyString(), anyString());
 * 
* *

38. Meta data and generic type retention (Since 2.1.0)

* *

* Mockito now preserves annotations on mocked methods and types as well as generic meta data. Previously, a mock type did not preserve * annotations on types unless they were explicitly inherited and never retained annotations on methods. As a consequence, the following * conditions now hold true: * *


 * {@literal @}{@code MyAnnotation
 *  class Foo {
 *    List bar() { ... }
 *  }
 *
 *  Class mockType = mock(Foo.class).getClass();
 *  assert mockType.isAnnotationPresent(MyAnnotation.class);
 *  assert mockType.getDeclaredMethod("bar").getGenericReturnType() instanceof ParameterizedType;
 * }
* *

* When using Java 8, Mockito now also preserves type annotations. This is default behavior and might not hold if an * alternative {@link org.mockito.plugins.MockMaker} is used. * *

39. Mocking final types, enums and final methods (Since 2.1.0)

* * Mockito now offers an {@link Incubating}, optional support for mocking final classes and methods. * This is a fantastic improvement that demonstrates Mockito's everlasting quest for improving testing experience. * Our ambition is that Mockito "just works" with final classes and methods. * Previously they were considered unmockable, preventing the user from mocking. * We already started discussing how to make this feature enabled by default. * Currently, the feature is still optional as we wait for more feedback from the community. * *

* This alternative mock maker which uses * a combination of both Java instrumentation API and sub-classing rather than creating a new class to represent * a mock. This way, it becomes possible to mock final types and methods. * *

* This mock maker is turned off by default because it is based on completely different mocking mechanism * that requires more feedback from the community. It can be activated explicitly by the mockito extension mechanism, * just create in the classpath a file /mockito-extensions/org.mockito.plugins.MockMaker * containing the value mock-maker-inline. * *

* As a convenience, the Mockito team provides an artifact where this mock maker is preconfigured. Instead of using the * mockito-core artifact, include the mockito-inline artifact in your project. Note that this artifact is * likely to be discontinued once mocking of final classes and methods gets integrated into the default mock maker. * *

* Some noteworthy notes about this mock maker: *

    *
  • Mocking final types and enums is incompatible with mock settings like : *
      *
    • explicitly serialization support withSettings().serializable()
    • *
    • extra-interfaces withSettings().extraInterfaces()
    • *
    *
  • *
  • Some methods cannot be mocked *
      *
    • Package-visible methods of java.*
    • *
    • native methods
    • *
    *
  • *
  • This mock maker has been designed around Java Agent runtime attachment ; this require a compatible JVM, * that is part of the JDK (or Java 9 VM). When running on a non-JDK VM prior to Java 9, it is however possible to * manually add the Byte Buddy Java agent jar using the -javaagent * parameter upon starting the JVM. *
  • *
* *

* If you are interested in more details of this feature please read the javadoc of * org.mockito.internal.creation.bytebuddy.InlineByteBuddyMockMaker * *

40. * Improved productivity and cleaner tests with "stricter" Mockito (Since 2.+)

* * To quickly find out how "stricter" Mockito can make you more productive and get your tests cleaner, see: *
    *
  • Strict stubbing with JUnit4 Rules - {@link MockitoRule#strictness(Strictness)} with {@link Strictness#STRICT_STUBS}
  • *
  • Strict stubbing with JUnit4 Runner - {@link Strict MockitoJUnitRunner.Strict}
  • *
  • Strict stubbing with JUnit5 Extension - org.mockito.junit.jupiter.MockitoExtension
  • *
  • Strict stubbing with TestNG Listener MockitoTestNGListener
  • *
  • Strict stubbing if you cannot use runner/rule - {@link MockitoSession}
  • *
  • Unnecessary stubbing detection with {@link MockitoJUnitRunner}
  • *
  • Stubbing argument mismatch warnings, documented in {@link MockitoHint}
  • *
* * Mockito is a "loose" mocking framework by default. * Mocks can be interacted with without setting any expectations beforehand. * This is intentional and it improves the quality of tests by forcing users to be explicit about what they want to stub / verify. * It is also very intuitive, easy to use and blends nicely with "given", "when", "then" template of clean test code. * This is also different from the classic mocking frameworks of the past, they were "strict" by default. *

* Being "loose" by default makes Mockito tests harder to debug at times. * There are scenarios where misconfigured stubbing (like using a wrong argument) forces the user to run the test with a debugger. * Ideally, tests failures are immediately obvious and don't require debugger to identify the root cause. * Starting with version 2.1 Mockito has been getting new features that nudge the framework towards "strictness". * We want Mockito to offer fantastic debuggability while not losing its core mocking style, optimized for * intuitiveness, explicitness and clean test code. *

* Help Mockito! Try the new features, give us feedback, join the discussion about Mockito strictness at GitHub * issue 769. * *

41. * Advanced public API for framework integrations (Since 2.10.+)

* * In Summer 2017 we decided that Mockito * * should offer better API * * for advanced framework integrations. * The new API is not intended for users who want to write unit tests. * It is intended for other test tools and mocking frameworks that need to extend or wrap Mockito with some custom logic. * During the design and implementation process (issue 1110) * we have developed and changed following public API elements: *
    *
  • New {@link MockitoPlugins} - * Enables framework integrators to get access to default Mockito plugins. * Useful when one needs to implement custom plugin such as {@link MockMaker} * and delegate some behavior to the default Mockito implementation. *
  • *
  • New {@link MockSettings#build(Class)} - * Creates immutable view of mock settings used later by Mockito. * Useful for creating invocations with {@link InvocationFactory} or when implementing custom {@link MockHandler}. *
  • *
  • New {@link MockingDetails#getMockHandler()} - * Other frameworks may use the mock handler to programmatically simulate invocations on mock objects. *
  • *
  • New {@link MockHandler#getMockSettings()} - * Useful to get hold of the setting the mock object was created with. *
  • *
  • New {@link InvocationFactory} - * Provides means to create instances of {@link Invocation} objects. * Useful for framework integrations that need to programmatically simulate method calls on mock objects. *
  • *
  • New {@link MockHandler#getInvocationContainer()} - * Provides access to invocation container object which has no methods (marker interface). * Container is needed to hide the internal implementation and avoid leaking it to the public API. *
  • *
  • Changed {@link org.mockito.stubbing.Stubbing} - * it now extends {@link Answer} interface. * It is backwards compatible because Stubbing interface is not extensible (see {@link NotExtensible}). * The change should be seamless to our users. *
  • *
  • {@link NotExtensible} - * Public annotation that indicates to the user that she should not provide custom implementations of given type. * Helps framework integrators and our users understand how to use Mockito API safely. *
  • *
* Do you have feedback? Please leave comment in issue 1110. * *

42. * New API for integrations: listening on verification start events (Since 2.11.+)

* * Framework integrations such as Spring Boot needs public API to tackle double-proxy use case * (issue 1191). * We added: *
    *
  • New {@link VerificationStartedListener} and {@link VerificationStartedEvent} * enable framework integrators to replace the mock object for verification. * The main driving use case is Spring Boot integration. * For details see Javadoc for {@link VerificationStartedListener}. *
  • *
  • New public method {@link MockSettings#verificationStartedListeners(VerificationStartedListener...)} * allows to supply verification started listeners at mock creation time. *
  • *
  • New handy method {@link MockingDetails#getMock()} was added to make the {@code MockingDetails} API more complete. * We found this method useful during the implementation. *
  • *
* *

43. * New API for integrations: MockitoSession is usable by testing frameworks (Since 2.15.+)

* *

{@link MockitoSessionBuilder} and {@link MockitoSession} were enhanced to enable reuse by testing framework * integrations (e.g. {@link MockitoRule} for JUnit):

*
    *
  • {@link MockitoSessionBuilder#initMocks(Object...)} allows to pass in multiple test class instances for * initialization of fields annotated with Mockito annotations like {@link org.mockito.Mock}. * This method is useful for advanced framework integrations (e.g. JUnit Jupiter), when a test uses multiple, * e.g. nested, test class instances. *
  • *
  • {@link MockitoSessionBuilder#name(String)} allows to pass a name from the testing framework to the * {@link MockitoSession} that will be used for printing warnings when {@link Strictness#WARN} is used. *
  • *
  • {@link MockitoSessionBuilder#logger(MockitoSessionLogger)} makes it possible to customize the logger used * for hints/warnings produced when finishing mocking (useful for testing and to connect reporting capabilities * provided by testing frameworks such as JUnit Jupiter). *
  • *
  • {@link MockitoSession#setStrictness(Strictness)} allows to change the strictness of a {@link MockitoSession} * for one-off scenarios, e.g. it enables configuring a default strictness for all tests in a class but makes it * possible to change the strictness for a single or a few tests. *
  • *
  • {@link MockitoSession#finishMocking(Throwable)} was added to avoid confusion that may arise because * there are multiple competing failures. It will disable certain checks when the supplied failure * is not {@code null}. *
  • *
* *

44. * Deprecated org.mockito.plugins.InstantiatorProvider as it was leaking internal API. it was * replaced by org.mockito.plugins.InstantiatorProvider2 (Since 2.15.4)

* *

org.mockito.plugins.InstantiatorProvider returned an internal API. Hence it was deprecated and replaced * by {@link org.mockito.plugins.InstantiatorProvider2}. org.mockito.plugins.InstantiatorProvider * has now been removed.

* *

45. New JUnit Jupiter (JUnit5+) extension

* * For integration with JUnit Jupiter (JUnit5+), use the `org.mockito:mockito-junit-jupiter` artifact. * For more information about the usage of the integration, see the JavaDoc of MockitoExtension. * *

46. * New Mockito.lenient() and MockSettings.lenient() methods (Since 2.20.0)

* * Strict stubbing feature is available since early Mockito 2. * It is very useful because it drives cleaner tests and improved productivity. * Strict stubbing reports unnecessary stubs, detects stubbing argument mismatch and makes the tests more DRY ({@link Strictness#STRICT_STUBS}). * This comes with a trade-off: in some cases, you may get false negatives from strict stubbing. * To remedy those scenarios you can now configure specific stubbing to be lenient, while all the other stubbings and mocks use strict stubbing: * *

 *   lenient().when(mock.foo()).thenReturn("ok");
 * 
* * If you want all the stubbings on a given mock to be lenient, you can configure the mock accordingly: * *

 *   Foo mock = Mockito.mock(Foo.class, withSettings().lenient());
 * 
* * For more information refer to {@link Mockito#lenient()}. * Let us know how do you find the new feature by opening a GitHub issue to discuss! * *

47. New API for clearing mock state in inline mocking (Since 2.25.0)

* * In certain specific, rare scenarios (issue #1619) * inline mocking causes memory leaks. * There is no clean way to mitigate this problem completely. * Hence, we introduced a new API to explicitly clear mock state (only make sense in inline mocking!). * See example usage in {@link MockitoFramework#clearInlineMocks()}. * If you have feedback or a better idea how to solve the problem please reach out. * * *

48. Mocking static methods (since 3.4.0)

* * When using the inline mock maker, it is possible to mock static method invocations within the current * thread and a user-defined scope. This way, Mockito assures that concurrently and sequentially running tests do not interfere. * * To make sure a static mock remains temporary, it is recommended to define the scope within a try-with-resources construct. * In the following example, the Foo type's static method would return foo unless mocked: * *

 * assertEquals("foo", Foo.method());
 * try (MockedStatic mocked = mockStatic(Foo.class)) {
 * mocked.when(Foo::method).thenReturn("bar");
 * assertEquals("bar", Foo.method());
 * mocked.verify(Foo::method);
 * }
 * assertEquals("foo", Foo.method());
 * 
* * Due to the defined scope of the static mock, it returns to its original behavior once the scope is released. To define mock * behavior and to verify static method invocations, use the MockedStatic that is returned. *

* *

49. Mocking object construction (since 3.5.0)

* * When using the inline mock maker, it is possible to generate mocks on constructor invocations within the current * thread and a user-defined scope. This way, Mockito assures that concurrently and sequentially running tests do not interfere. * * To make sure a constructor mocks remain temporary, it is recommended to define the scope within a try-with-resources construct. * In the following example, the Foo type's construction would generate a mock: * *

 * assertEquals("foo", new Foo().method());
 * try (MockedConstruction mocked = mockConstruction(Foo.class)) {
 * Foo foo = new Foo();
 * when(foo.method()).thenReturn("bar");
 * assertEquals("bar", foo.method());
 * verify(foo).method();
 * }
 * assertEquals("foo", new Foo().method());
 * 
* * Due to the defined scope of the mocked construction, object construction returns to its original behavior once the scope is * released. To define mock behavior and to verify method invocations, use the MockedConstruction that is returned. *

* *

50. Avoiding code generation when only interfaces are mocked (since 3.12.2)

* * The JVM offers the {@link java.lang.reflect.Proxy} facility for creating dynamic proxies of interface types. For most applications, Mockito * must be capable of mocking classes as supported by the default mock maker, or even final classes, as supported by the inline mock maker. To * create such mocks, Mockito requires to setup diverse JVM facilities and must apply code generation. If only interfaces are supposed to be * mocked, one can however choose to use a org.mockito.internal.creation.proxy.ProxyMockMaker that is based on the {@link java.lang.reflect.Proxy} * API which avoids diverse overhead of the other mock makers but also limits mocking to interfaces. * * This mock maker can be activated explicitly by the mockito extension mechanism, just create in the classpath a file * /mockito-extensions/org.mockito.plugins.MockMaker containing the value mock-maker-proxy. * *

51. Mark classes as unmockable (since 4.1.0)

* * In some cases, mocking a class/interface can lead to unexpected runtime behavior. For example, mocking a java.util.List * is difficult, given the requirements imposed by the interface. This means that on runtime, depending on what methods the application * calls on the list, your mock might behave in such a way that it violates the interface. * *

* For any class/interface you own that is problematic to mock, you can now mark the class with {@link org.mockito.DoNotMock @DoNotMock}. For usage * of the annotation and how to ship your own (to avoid a compile time dependency on a test artifact), please see its JavaDoc. *

* *

52. * New strictness attribute for @Mock annotation and MockSettings.strictness() methods (Since 4.6.0)

* * You can now customize the strictness level for a single mock, either using `@Mock` annotation strictness attribute or * using `MockSettings.strictness()`. This can be useful if you want all of your mocks to be strict, * but one of the mocks to be lenient. * *

 *   @Mock(strictness = Strictness.LENIENT)
 *   Foo mock;
 *   // using MockSettings.withSettings()
 *   Foo mock = Mockito.mock(Foo.class, withSettings().strictness(Strictness.WARN));
 * 
* *

53. * Specifying mock maker for individual mocks (Since 4.8.0)

* * You may encounter situations where you want to use a different mock maker for a specific test only. * For example, you might want to migrate to the inline mock maker, but a few test do not work right away. * In such case, you can (temporarily) use {@link MockSettings#mockMaker(String)} and {@link Mock#mockMaker()} * to specify the mock maker for a specific mock which is causing the problem. * *

 *   // using annotation
 *   @Mock(mockMaker = MockMakers.SUBCLASS)
 *   Foo mock;
 *   // using MockSettings.withSettings()
 *   Foo mock = Mockito.mock(Foo.class, withSettings().mockMaker(MockMakers.SUBCLASS));
 * 
* *

54. * Mocking/spying without specifying class (Since 4.9.0)

* * Instead of calling method {@link Mockito#mock(Class)} or {@link Mockito#spy(Class)} with Class parameter, you can now * now call method {@code mock()} or {@code spy()} without parameters: * *

 *   Foo foo = Mockito.mock();
 *   Bar bar = Mockito.spy();
 * 
* * Mockito will automatically detect the needed class. *

* It works only if you assign result of {@code mock()} or {@code spy()} to a variable or field with an explicit type. * With an implicit type, the Java compiler is unable to automatically determine the type of a mock and you need * to pass in the {@code Class} explicitly. *

* *

55. * Verification with assertions (Since 5.3.0)

* * To validate arguments during verification, instead of capturing them with {@link ArgumentCaptor}, you can now * use {@link ArgumentMatchers#assertArg(Consumer)}}: * *

 *   verify(serviceMock).doStuff(assertArg(param -> {
 *     assertThat(param.getField1()).isEqualTo("foo");
 *     assertThat(param.getField2()).isEqualTo("bar");
 *   }));
 * 
*/ @CheckReturnValue @SuppressWarnings("unchecked") public class Mockito extends ArgumentMatchers { static final MockitoCore MOCKITO_CORE = new MockitoCore(); /** * The default Answer of every mock if the mock was not stubbed. * * Typically, it just returns some empty value. *

* {@link Answer} can be used to define the return values of un-stubbed invocations. *

* This implementation first tries the global configuration and if there is no global configuration then * it will use a default answer that returns zeros, empty collections, nulls, etc. */ public static final Answer RETURNS_DEFAULTS = Answers.RETURNS_DEFAULTS; /** * Optional Answer to be used with {@link Mockito#mock(Class, Answer)}. *

* {@link Answer} can be used to define the return values of un-stubbed invocations. *

* This implementation can be helpful when working with legacy code. * Un-stubbed methods often return null. If your code uses the object returned by an un-stubbed call, * you get a NullPointerException. * This implementation of Answer returns SmartNull instead of null. * SmartNull gives nicer exception messages than NPEs, because it points out the * line where the un-stubbed method was called. You just click on the stack trace. *

* ReturnsSmartNulls first tries to return ordinary values (zeros, empty collections, empty string, etc.) * then it tries to return SmartNull. If the return type is final then plain null is returned. *

* Example: *


     *   Foo mock = mock(Foo.class, RETURNS_SMART_NULLS);
     *
     *   //calling un-stubbed method here:
     *   Stuff stuff = mock.getStuff();
     *
     *   //using object returned by un-stubbed call:
     *   stuff.doSomething();
     *
     *   //Above doesn't yield NullPointerException this time!
     *   //Instead, SmartNullPointerException is thrown.
     *   //Exception's cause links to un-stubbed mock.getStuff() - just click on the stack trace.
     * 
*/ public static final Answer RETURNS_SMART_NULLS = Answers.RETURNS_SMART_NULLS; /** * Optional Answer to be used with {@link Mockito#mock(Class, Answer)} *

* {@link Answer} can be used to define the return values of un-stubbed invocations. *

* This implementation can be helpful when working with legacy code. *

* ReturnsMocks first tries to return ordinary values (zeros, empty collections, empty string, etc.) * then it tries to return mocks. If the return type cannot be mocked (e.g. is final) then plain null is returned. *

*/ public static final Answer RETURNS_MOCKS = Answers.RETURNS_MOCKS; /** * Optional Answer to be used with {@link Mockito#mock(Class, Answer)}. *

* Example that shows how deep stub works: *


     *   Foo mock = mock(Foo.class, RETURNS_DEEP_STUBS);
     *
     *   // note that we're stubbing a chain of methods here: getBar().getName()
     *   when(mock.getBar().getName()).thenReturn("deep");
     *
     *   // note that we're chaining method calls: getBar().getName()
     *   assertEquals("deep", mock.getBar().getName());
     * 
*

* *

* WARNING: * This feature should rarely be required for regular clean code! Leave it for legacy code. * Mocking a mock to return a mock, to return a mock, (...), to return something meaningful * hints at violation of Law of Demeter or mocking a value object (a well known anti-pattern). *

* *

* Good quote I've seen one day on the web: every time a mock returns a mock a fairy dies. *

* *

* Please note that this answer will return existing mocks that matches the stub. This * behavior is ok with deep stubs and allows verification to work on the last mock of the chain. *


     *   when(mock.getBar(anyString()).getThingy().getName()).thenReturn("deep");
     *
     *   mock.getBar("candy bar").getThingy().getName();
     *
     *   assertSame(mock.getBar(anyString()).getThingy().getName(), mock.getBar(anyString()).getThingy().getName());
     *   verify(mock.getBar("candy bar").getThingy()).getName();
     *   verify(mock.getBar(anyString()).getThingy()).getName();
     * 
*

* *

* Verification only works with the last mock in the chain. You can use verification modes. *


     *   when(person.getAddress(anyString()).getStreet().getName()).thenReturn("deep");
     *   when(person.getAddress(anyString()).getStreet(Locale.ITALIAN).getName()).thenReturn("deep");
     *   when(person.getAddress(anyString()).getStreet(Locale.CHINESE).getName()).thenReturn("deep");
     *
     *   person.getAddress("the docks").getStreet().getName();
     *   person.getAddress("the docks").getStreet().getLongName();
     *   person.getAddress("the docks").getStreet(Locale.ITALIAN).getName();
     *   person.getAddress("the docks").getStreet(Locale.CHINESE).getName();
     *
     *   // note that we are actually referring to the very last mock in the stubbing chain.
     *   InOrder inOrder = inOrder(
     *       person.getAddress("the docks").getStreet(),
     *       person.getAddress("the docks").getStreet(Locale.CHINESE),
     *       person.getAddress("the docks").getStreet(Locale.ITALIAN)
     *   );
     *   inOrder.verify(person.getAddress("the docks").getStreet(), times(1)).getName();
     *   inOrder.verify(person.getAddress("the docks").getStreet()).getLongName();
     *   inOrder.verify(person.getAddress("the docks").getStreet(Locale.ITALIAN), atLeast(1)).getName();
     *   inOrder.verify(person.getAddress("the docks").getStreet(Locale.CHINESE)).getName();
     * 
*

* *

* How deep stub work internally? *


     *   //this:
     *   Foo mock = mock(Foo.class, RETURNS_DEEP_STUBS);
     *   when(mock.getBar().getName(), "deep");
     *
     *   //is equivalent of
     *   Foo foo = mock(Foo.class);
     *   Bar bar = mock(Bar.class);
     *   when(foo.getBar()).thenReturn(bar);
     *   when(bar.getName()).thenReturn("deep");
     * 
*

* *

* This feature will not work when any return type of methods included in the chain cannot be mocked * (for example: is a primitive or a final class). This is because of java type system. *

*/ public static final Answer RETURNS_DEEP_STUBS = Answers.RETURNS_DEEP_STUBS; /** * Optional Answer to be used with {@link Mockito#mock(Class, Answer)} * *

* {@link Answer} can be used to define the return values of un-stubbed invocations. *

* This implementation can be helpful when working with legacy code. * When this implementation is used, un-stubbed methods will delegate to the real implementation. * This is a way to create a partial mock object that calls real methods by default. *

* As usual, you are going to read the partial mock warning: * Object oriented programming is more-or-less tackling complexity by dividing the complexity into separate, specific, SRPy objects. * How does partial mock fit into this paradigm? Well, it just doesn't... * Partial mock usually means that the complexity has been moved to a different method on the same object. * In most cases, this is not the way you want to design your application. *

* However, there are rare cases when partial mocks come handy: * dealing with code you cannot change easily (3rd party interfaces, interim refactoring of legacy code etc.) * However, I wouldn't use partial mocks for new, test-driven and well-designed code. *

* Example: *


     * Foo mock = mock(Foo.class, CALLS_REAL_METHODS);
     *
     * // this calls the real implementation of Foo.getSomething()
     * value = mock.getSomething();
     *
     * doReturn(fakeValue).when(mock).getSomething();
     *
     * // now fakeValue is returned
     * value = mock.getSomething();
     * 
* *

* Note 1: Stubbing partial mocks using when(mock.getSomething()).thenReturn(fakeValue) * syntax will call the real method. For partial mock it's recommended to use doReturn syntax. *

* Note 2: If the mock is serialized then deserialized, then this answer will not be able to understand * generics metadata. */ public static final Answer CALLS_REAL_METHODS = Answers.CALLS_REAL_METHODS; /** * Optional Answer to be used with {@link Mockito#mock(Class, Answer)}. * * Allows Builder mocks to return itself whenever a method is invoked that returns a Type equal * to the class or a superclass. * *

Keep in mind this answer uses the return type of a method. * If this type is assignable to the class of the mock, it will return the mock. * Therefore if you have a method returning a superclass (for example {@code Object}) it will match and return the mock.

* * Consider a HttpBuilder used in a HttpRequesterWithHeaders. * *

     * public class HttpRequesterWithHeaders {
     *
     *      private HttpBuilder builder;
     *
     *      public HttpRequesterWithHeaders(HttpBuilder builder) {
     *          this.builder = builder;
     *      }
     *
     *      public String request(String uri) {
     *          return builder.withUrl(uri)
     *                  .withHeader("Content-type: application/json")
     *                  .withHeader("Authorization: Bearer")
     *                  .request();
     *      }
     *  }
     *
     *  private static class HttpBuilder {
     *
     *      private String uri;
     *      private List<String> headers;
     *
     *      public HttpBuilder() {
     *          this.headers = new ArrayList<String>();
     *      }
     *
     *       public HttpBuilder withUrl(String uri) {
     *           this.uri = uri;
     *           return this;
     *       }
     *
     *       public HttpBuilder withHeader(String header) {
     *           this.headers.add(header);
     *           return this;
     *       }
     *
     *       public String request() {
     *          return uri + headers.toString();
     *       }
     *  }
     * 
* * The following test will succeed * *

     * @Test
     *  public void use_full_builder_with_terminating_method() {
     *      HttpBuilder builder = mock(HttpBuilder.class, RETURNS_SELF);
     *      HttpRequesterWithHeaders requester = new HttpRequesterWithHeaders(builder);
     *      String response = "StatusCode: 200";
     *
     *      when(builder.request()).thenReturn(response);
     *
     *      assertThat(requester.request("URI")).isEqualTo(response);
     *  }
     * 
*/ public static final Answer RETURNS_SELF = Answers.RETURNS_SELF; /** * Creates a mock object of the requested class or interface. *

* See examples in javadoc for the {@link Mockito} class. * * @param reified don't pass any values to it. It's a trick to detect the class/interface you * want to mock. * @return the mock object. * @since 4.9.0 */ @SafeVarargs public static T mock(T... reified) { return mock(withSettings(), reified); } /** * Creates a mock object of the requested class or interface with the given default answer. *

* See examples in javadoc for the {@link Mockito} class. * * @param defaultAnswer the default answer to use. * @param reified don't pass any values to it. It's a trick to detect the class/interface you * want to mock. * @return the mock object. */ @SafeVarargs public static T mock(@SuppressWarnings("rawtypes") Answer defaultAnswer, T... reified) { return mock(withSettings().defaultAnswer(defaultAnswer), reified); } /** * Creates a mock object of the requested class or interface with the given name. *

* See examples in javadoc for the {@link Mockito} class. * * @param name the mock name to use. * @param reified don't pass any values to it. It's a trick to detect the class/interface you * want to mock. * @return the mock object. */ @SafeVarargs public static T mock(String name, T... reified) { return mock(withSettings().name(name).defaultAnswer(RETURNS_DEFAULTS), reified); } /** * Creates a mock object of the requested class or interface with the given settings. *

* See examples in javadoc for the {@link Mockito} class. * * @param settings the mock settings to use. * @param reified don't pass any values to it. It's a trick to detect the class/interface you * want to mock. * @return the mock object. */ @SafeVarargs public static T mock(MockSettings settings, T... reified) { if (reified == null || reified.length > 0) { throw new IllegalArgumentException( "Please don't pass any values here. Java will detect class automagically."); } return mock(getClassOf(reified), settings); } /** * Creates mock object of given class or interface. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock class or interface to mock * @return mock object */ public static T mock(Class classToMock) { return mock(classToMock, withSettings()); } /** * Specifies mock name. Naming mocks can be helpful for debugging - the name is used in all verification errors. *

* Beware that naming mocks is not a solution for complex code which uses too many mocks or collaborators. * If you have too many mocks then refactor the code so that it's easy to test/debug without necessity of naming mocks. *

* If you use @Mock annotation then you've got naming mocks for free! @Mock uses field name as mock name. {@link Mock Read more.} *

* * See examples in javadoc for {@link Mockito} class * * @param classToMock class or interface to mock * @param name of the mock * @return mock object */ public static T mock(Class classToMock, String name) { return mock(classToMock, withSettings().name(name).defaultAnswer(RETURNS_DEFAULTS)); } /** * Returns a MockingDetails instance that enables inspecting a particular object for Mockito related information. * Can be used to find out if given object is a Mockito mock * or to find out if a given mock is a spy or mock. *

* In future Mockito versions MockingDetails may grow and provide other useful information about the mock, * e.g. invocations, stubbing info, etc. * * @param toInspect - object to inspect. null input is allowed. * @return A {@link org.mockito.MockingDetails} instance. * @since 1.9.5 */ public static MockingDetails mockingDetails(Object toInspect) { return MOCKITO_CORE.mockingDetails(toInspect); } /** * Creates mock with a specified strategy for its answers to interactions. * It's quite an advanced feature and typically you don't need it to write decent tests. * However it can be helpful when working with legacy systems. *

* It is the default answer so it will be used only when you don't stub the method call. * *


     *   Foo mock = mock(Foo.class, RETURNS_SMART_NULLS);
     *   Foo mockTwo = mock(Foo.class, new YourOwnAnswer());
     * 
* *

See examples in javadoc for {@link Mockito} class

* * @param classToMock class or interface to mock * @param defaultAnswer default answer for un-stubbed methods * * @return mock object */ public static T mock(Class classToMock, Answer defaultAnswer) { return mock(classToMock, withSettings().defaultAnswer(defaultAnswer)); } /** * Creates a mock with some non-standard settings. *

* The number of configuration points for a mock will grow, * so we need a fluent way to introduce new configuration without adding more and more overloaded Mockito.mock() methods. * Hence {@link MockSettings}. *


     *   Listener mock = mock(Listener.class, withSettings()
     *     .name("firstListner").defaultBehavior(RETURNS_SMART_NULLS));
     *   );
     * 
* Use it carefully and occasionally. What might be reason your test needs non-standard mocks? * Is the code under test so complicated that it requires non-standard mocks? * Wouldn't you prefer to refactor the code under test, so that it is testable in a simple way? *

* See also {@link Mockito#withSettings()} *

* See examples in javadoc for {@link Mockito} class * * @param classToMock class or interface to mock * @param mockSettings additional mock settings * @return mock object */ public static T mock(Class classToMock, MockSettings mockSettings) { return MOCKITO_CORE.mock(classToMock, mockSettings); } /** * Creates a spy of the real object. The spy calls real methods unless they are stubbed. *

* Real spies should be used carefully and occasionally, for example when dealing with legacy code. *

* As usual, you are going to read the partial mock warning: * Object oriented programming tackles complexity by dividing the complexity into separate, specific, SRPy objects. * How does partial mock fit into this paradigm? Well, it just doesn't... * Partial mock usually means that the complexity has been moved to a different method on the same object. * In most cases, this is not the way you want to design your application. *

* However, there are rare cases when partial mocks come handy: * dealing with code you cannot change easily (3rd party interfaces, interim refactoring of legacy code etc.) * However, I wouldn't use partial mocks for new, test-driven and well-designed code. *

* Example: * *


     *   List list = new LinkedList();
     *   List spy = spy(list);
     *
     *   //optionally, you can stub out some methods:
     *   when(spy.size()).thenReturn(100);
     *
     *   //using the spy calls real methods
     *   spy.add("one");
     *   spy.add("two");
     *
     *   //prints "one" - the first element of a list
     *   System.out.println(spy.get(0));
     *
     *   //size() method was stubbed - 100 is printed
     *   System.out.println(spy.size());
     *
     *   //optionally, you can verify
     *   verify(spy).add("one");
     *   verify(spy).add("two");
     * 
* *

Important gotcha on spying real objects!

*
    *
  1. Sometimes it's impossible or impractical to use {@link Mockito#when(Object)} for stubbing spies. * Therefore for spies it is recommended to always use doReturn|Answer|Throw()|CallRealMethod * family of methods for stubbing. Example: * *
    
         *   List list = new LinkedList();
         *   List spy = spy(list);
         *
         *   //Impossible: real method is called so spy.get(0) throws IndexOutOfBoundsException (the list is yet empty)
         *   when(spy.get(0)).thenReturn("foo");
         *
         *   //You have to use doReturn() for stubbing
         *   doReturn("foo").when(spy).get(0);
         * 
    *
  2. * *
  3. Mockito *does not* delegate calls to the passed real instance, instead it actually creates a copy of it. * So if you keep the real instance and interact with it, don't expect the spied to be aware of those interaction * and their effect on real instance state. * The corollary is that when an *un-stubbed* method is called *on the spy* but *not on the real instance*, * you won't see any effects on the real instance.
  4. * *
  5. Watch out for final methods. * Mockito doesn't mock final methods so the bottom line is: when you spy on real objects + you try to stub a final method = trouble. * Also you won't be able to verify those method as well. *
  6. *
*

* See examples in javadoc for {@link Mockito} class * *

Note that the spy won't have any annotations of the spied type, because CGLIB won't rewrite them. * It may troublesome for code that rely on the spy to have these annotations.

* * * @param object * to spy on * @return a spy of the real object */ public static T spy(T object) { return MOCKITO_CORE.mock( (Class) object.getClass(), withSettings().spiedInstance(object).defaultAnswer(CALLS_REAL_METHODS)); } /** * Please refer to the documentation of {@link #spy(Object)}. * Overusing spies hints at code design smells. *

* This method, in contrast to the original {@link #spy(Object)}, creates a spy based on class instead of an object. * Sometimes it is more convenient to create spy based on the class and avoid providing an instance of a spied object. * This is particularly useful for spying on abstract classes because they cannot be instantiated. * See also {@link MockSettings#useConstructor(Object...)}. *

* Examples: *


     *   SomeAbstract spy = spy(SomeAbstract.class);
     *
     *   //Robust API, via settings builder:
     *   OtherAbstract spy = mock(OtherAbstract.class, withSettings()
     *      .useConstructor().defaultAnswer(CALLS_REAL_METHODS));
     *
     *   //Mocking a non-static inner abstract class:
     *   InnerAbstract spy = mock(InnerAbstract.class, withSettings()
     *      .useConstructor().outerInstance(outerInstance).defaultAnswer(CALLS_REAL_METHODS));
     * 
* * @param classToSpy the class to spy * @param type of the spy * @return a spy of the provided class * @since 1.10.12 */ public static T spy(Class classToSpy) { return MOCKITO_CORE.mock( classToSpy, withSettings().useConstructor().defaultAnswer(CALLS_REAL_METHODS)); } /** * Please refer to the documentation of {@link #spy(Class)}. * * @param reified don't pass any values to it. It's a trick to detect the class/interface you want to mock. * @return spy object * @since 4.9.0 */ @SafeVarargs public static T spy(T... reified) { if (reified.length > 0) { throw new IllegalArgumentException( "Please don't pass any values here. Java will detect class automagically."); } return spy(getClassOf(reified)); } private static Class getClassOf(T[] array) { return (Class) array.getClass().getComponentType(); } /** * Creates a thread-local mock controller for all static methods of the given class or interface. * The returned object's {@link MockedStatic#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* Note: We recommend against mocking static methods of classes in the standard library or * classes used by custom class loaders used to execute the block with the mocked class. A mock * maker might forbid mocking static methods of know classes that are known to cause problems. * Also, if a static method is a JVM-intrinsic, it cannot typically be mocked even if not * explicitly forbidden. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock class or interface of which static mocks should be mocked. * @return mock controller */ public static MockedStatic mockStatic(Class classToMock) { return mockStatic(classToMock, withSettings()); } /** * Creates a thread-local mock controller for all static methods of the given class or interface. * The returned object's {@link MockedStatic#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* Note: We recommend against mocking static methods of classes in the standard library or * classes used by custom class loaders used to execute the block with the mocked class. A mock * maker might forbid mocking static methods of know classes that are known to cause problems. * Also, if a static method is a JVM-intrinsic, it cannot typically be mocked even if not * explicitly forbidden. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock class or interface of which static mocks should be mocked. * @param defaultAnswer the default answer when invoking static methods. * @return mock controller */ public static MockedStatic mockStatic(Class classToMock, Answer defaultAnswer) { return mockStatic(classToMock, withSettings().defaultAnswer(defaultAnswer)); } /** * Creates a thread-local mock controller for all static methods of the given class or interface. * The returned object's {@link MockedStatic#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* Note: We recommend against mocking static methods of classes in the standard library or * classes used by custom class loaders used to execute the block with the mocked class. A mock * maker might forbid mocking static methods of know classes that are known to cause problems. * Also, if a static method is a JVM-intrinsic, it cannot typically be mocked even if not * explicitly forbidden. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock class or interface of which static mocks should be mocked. * @param name the name of the mock to use in error messages. * @return mock controller */ public static MockedStatic mockStatic(Class classToMock, String name) { return mockStatic(classToMock, withSettings().name(name)); } /** * Creates a thread-local mock controller for all static methods of the given class or interface. * The returned object's {@link MockedStatic#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* Note: We recommend against mocking static methods of classes in the standard library or * classes used by custom class loaders used to execute the block with the mocked class. A mock * maker might forbid mocking static methods of know classes that are known to cause problems. * Also, if a static method is a JVM-intrinsic, it cannot typically be mocked even if not * explicitly forbidden. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock class or interface of which static mocks should be mocked. * @param mockSettings the settings to use where only name and default answer are considered. * @return mock controller */ public static MockedStatic mockStatic(Class classToMock, MockSettings mockSettings) { return MOCKITO_CORE.mockStatic(classToMock, mockSettings); } /** * Creates a thread-local mock controller for all constructions of the given class. * The returned object's {@link MockedConstruction#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock non-abstract class of which constructions should be mocked. * @param defaultAnswer the default answer for the first created mock. * @param additionalAnswers the default answer for all additional mocks. For any access mocks, the * last answer is used. If this array is empty, the {@code defaultAnswer} is used. * @return mock controller */ public static MockedConstruction mockConstructionWithAnswer( Class classToMock, Answer defaultAnswer, Answer... additionalAnswers) { return mockConstruction( classToMock, context -> { if (context.getCount() == 1 || additionalAnswers.length == 0) { return withSettings().defaultAnswer(defaultAnswer); } else if (context.getCount() > additionalAnswers.length) { return withSettings() .defaultAnswer(additionalAnswers[additionalAnswers.length - 1]); } else { return withSettings() .defaultAnswer(additionalAnswers[context.getCount() - 2]); } }, (mock, context) -> {}); } /** * Creates a thread-local mock controller for all constructions of the given class. * The returned object's {@link MockedConstruction#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock non-abstract class of which constructions should be mocked. * @return mock controller */ public static MockedConstruction mockConstruction(Class classToMock) { return mockConstruction(classToMock, index -> withSettings(), (mock, context) -> {}); } /** * Creates a thread-local mock controller for all constructions of the given class. * The returned object's {@link MockedConstruction#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock non-abstract class of which constructions should be mocked. * @param mockInitializer a callback to prepare the methods on a mock after its instantiation. * @return mock controller */ public static MockedConstruction mockConstruction( Class classToMock, MockedConstruction.MockInitializer mockInitializer) { return mockConstruction(classToMock, withSettings(), mockInitializer); } /** * Creates a thread-local mock controller for all constructions of the given class. * The returned object's {@link MockedConstruction#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock non-abstract class of which constructions should be mocked. * @param mockSettings the mock settings to use. * @return mock controller */ public static MockedConstruction mockConstruction( Class classToMock, MockSettings mockSettings) { return mockConstruction(classToMock, context -> mockSettings); } /** * Creates a thread-local mock controller for all constructions of the given class. * The returned object's {@link MockedConstruction#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock non-abstract class of which constructions should be mocked. * @param mockSettingsFactory the mock settings to use. * @return mock controller */ public static MockedConstruction mockConstruction( Class classToMock, Function mockSettingsFactory) { return mockConstruction(classToMock, mockSettingsFactory, (mock, context) -> {}); } /** * Creates a thread-local mock controller for all constructions of the given class. * The returned object's {@link MockedConstruction#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock non-abstract class of which constructions should be mocked. * @param mockSettings the settings to use. * @param mockInitializer a callback to prepare the methods on a mock after its instantiation. * @return mock controller */ public static MockedConstruction mockConstruction( Class classToMock, MockSettings mockSettings, MockedConstruction.MockInitializer mockInitializer) { return mockConstruction(classToMock, index -> mockSettings, mockInitializer); } /** * Creates a thread-local mock controller for all constructions of the given class. * The returned object's {@link MockedConstruction#close()} method must be called upon completing the * test or the mock will remain active on the current thread. *

* See examples in javadoc for {@link Mockito} class * * @param classToMock non-abstract class of which constructions should be mocked. * @param mockSettingsFactory a function to create settings to use. * @param mockInitializer a callback to prepare the methods on a mock after its instantiation. * @return mock controller */ public static MockedConstruction mockConstruction( Class classToMock, Function mockSettingsFactory, MockedConstruction.MockInitializer mockInitializer) { return MOCKITO_CORE.mockConstruction(classToMock, mockSettingsFactory, mockInitializer); } /** * Enables stubbing methods. Use it when you want the mock to return particular value when particular method is called. *

* Simply put: "When the x method is called then return y". * *

* Examples: * *


     * when(mock.someMethod()).thenReturn(10);
     *
     * //you can use flexible argument matchers, e.g:
     * when(mock.someMethod(anyString())).thenReturn(10);
     *
     * //setting exception to be thrown:
     * when(mock.someMethod("some arg")).thenThrow(new RuntimeException());
     *
     * //you can set different behavior for consecutive method calls.
     * //Last stubbing (e.g: thenReturn("foo")) determines the behavior of further consecutive calls.
     * when(mock.someMethod("some arg"))
     *  .thenThrow(new RuntimeException())
     *  .thenReturn("foo");
     *
     * //Alternative, shorter version for consecutive stubbing:
     * when(mock.someMethod("some arg"))
     *  .thenReturn("one", "two");
     * //is the same as:
     * when(mock.someMethod("some arg"))
     *  .thenReturn("one")
     *  .thenReturn("two");
     *
     * //shorter version for consecutive method calls throwing exceptions:
     * when(mock.someMethod("some arg"))
     *  .thenThrow(new RuntimeException(), new NullPointerException();
     *
     * 
* * For stubbing void methods with throwables see: {@link Mockito#doThrow(Throwable...)} *

* Stubbing can be overridden: for example common stubbing can go to fixture * setup but the test methods can override it. * Please note that overriding stubbing is a potential code smell that points out too much stubbing. *

* Once stubbed, the method will always return stubbed value regardless * of how many times it is called. *

* Last stubbing is more important - when you stubbed the same method with * the same arguments many times. *

* Although it is possible to verify a stubbed invocation, usually it's just redundant. * Let's say you've stubbed foo.bar(). * If your code cares what foo.bar() returns then something else breaks(often before even verify() gets executed). * If your code doesn't care what get(0) returns then it should not be stubbed. * *

* See examples in javadoc for {@link Mockito} class * @param methodCall method to be stubbed * @return OngoingStubbing object used to stub fluently. * Do not create a reference to this returned object. */ public static OngoingStubbing when(T methodCall) { return MOCKITO_CORE.when(methodCall); } /** * Verifies certain behavior happened once. *

* Alias to verify(mock, times(1)) E.g: *


     *   verify(mock).someMethod("some arg");
     * 
* Above is equivalent to: *

     *   verify(mock, times(1)).someMethod("some arg");
     * 
*

* Arguments passed are compared using equals() method. * Read about {@link ArgumentCaptor} or {@link ArgumentMatcher} to find out other ways of matching / asserting arguments passed. *

* Although it is possible to verify a stubbed invocation, usually it's just redundant. * Let's say you've stubbed foo.bar(). * If your code cares what foo.bar() returns then something else breaks(often before even verify() gets executed). * If your code doesn't care what foo.bar() returns then it should not be stubbed. * *

* See examples in javadoc for {@link Mockito} class * * @param mock to be verified * @return mock object itself */ public static T verify(T mock) { return MOCKITO_CORE.verify(mock, times(1)); } /** * Verifies certain behavior happened at least once / exact number of times / never. E.g: *


     *   verify(mock, times(5)).someMethod("was called five times");
     *
     *   verify(mock, atLeast(2)).someMethod("was called at least two times");
     *
     *   //you can use flexible argument matchers, e.g:
     *   verify(mock, atLeastOnce()).someMethod(anyString());
     * 
* * times(1) is the default and can be omitted *

* Arguments passed are compared using equals() method. * Read about {@link ArgumentCaptor} or {@link ArgumentMatcher} to find out other ways of matching / asserting arguments passed. *

* * @param mock to be verified * @param mode times(x), atLeastOnce() or never() * * @return mock object itself */ public static T verify(T mock, VerificationMode mode) { return MOCKITO_CORE.verify(mock, mode); } /** * Smart Mockito users hardly use this feature because they know it could be a sign of poor tests. * Normally, you don't need to reset your mocks, just create new mocks for each test method. *

* Instead of #reset() please consider writing simple, small and focused test methods over lengthy, over-specified tests. * First potential code smell is reset() in the middle of the test method. This probably means you're testing too much. * Follow the whisper of your test methods: "Please keep us small and focused on single behavior". * There are several threads about it on mockito mailing list. *

* The only reason we added reset() method is to * make it possible to work with container-injected mocks. * For more information see the FAQ (here). *

* Don't harm yourself. reset() in the middle of the test method is a code smell (you're probably testing too much). *


     *   List mock = mock(List.class);
     *   when(mock.size()).thenReturn(10);
     *   mock.add(1);
     *
     *   reset(mock);
     *   //at this point the mock forgot any interactions and stubbing
     * 
* * @param The Type of the mocks * @param mocks to be reset */ public static void reset(T... mocks) { MOCKITO_CORE.reset(mocks); } /** * Clears all mocks, type caches and instrumentations. *

* By clearing Mockito's state, previously created mocks might begin to malfunction. This option can be used if * Mockito's caches take up too much space or if the inline mock maker's instrumentation is causing performance * issues in code where mocks are no longer used. Normally, you would not need to use this option. */ public static void clearAllCaches() { MOCKITO_CORE.clearAllCaches(); } /** * Use this method in order to only clear invocations, when stubbing is non-trivial. Use-cases can be: *

    *
  • You are using a dependency injection framework to inject your mocks.
  • *
  • The mock is used in a stateful scenario. For example a class is Singleton which depends on your mock.
  • *
* * Try to avoid this method at all costs. Only clear invocations if you are unable to efficiently test your program. * @param The type of the mocks * @param mocks The mocks to clear the invocations for */ public static void clearInvocations(T... mocks) { MOCKITO_CORE.clearInvocations(mocks); } /** * Checks if any of given mocks has any unverified interaction. *

* You can use this method after you verified your mocks - to make sure that nothing * else was invoked on your mocks. *

* See also {@link Mockito#never()} - it is more explicit and communicates the intent well. *

* Stubbed invocations (if called) are also treated as interactions. * If you want stubbed invocations automatically verified, check out {@link Strictness#STRICT_STUBS} feature * introduced in Mockito 2.3.0. * If you want to ignore stubs for verification, see {@link #ignoreStubs(Object...)}. *

* A word of warning: * Some users who did a lot of classic, expect-run-verify mocking tend to use verifyNoMoreInteractions() very often, even in every test method. * verifyNoMoreInteractions() is not recommended to use in every test method. * verifyNoMoreInteractions() is a handy assertion from the interaction testing toolkit. Use it only when it's relevant. * Abusing it leads to over-specified, less maintainable tests. *

* This method will also detect unverified invocations that occurred before the test method, * for example: in setUp(), @Before method or in constructor. * Consider writing nice code that makes interactions only in test methods. * *

* Example: * *


     * //interactions
     * mock.doSomething();
     * mock.doSomethingUnexpected();
     *
     * //verification
     * verify(mock).doSomething();
     *
     * //following will fail because 'doSomethingUnexpected()' is unexpected
     * verifyNoMoreInteractions(mock);
     *
     * 
* * See examples in javadoc for {@link Mockito} class * * @param mocks to be verified */ public static void verifyNoMoreInteractions(Object... mocks) { MOCKITO_CORE.verifyNoMoreInteractions(mocks); } /** * Verifies that no interactions happened on given mocks. *

     *   verifyNoInteractions(mockOne, mockTwo);
     * 
* This method will also detect invocations * that occurred before the test method, for example: in setUp(), @Before method or in constructor. * Consider writing nice code that makes interactions only in test methods. *

* See also {@link Mockito#never()} - it is more explicit and communicates the intent well. *

* See examples in javadoc for {@link Mockito} class * * @param mocks to be verified * @since 3.0.1 */ public static void verifyNoInteractions(Object... mocks) { MOCKITO_CORE.verifyNoInteractions(mocks); } /** * Use doThrow() when you want to stub the void method with an exception. *

* Stubbing voids requires different approach from {@link Mockito#when(Object)} because the compiler * does not like void methods inside brackets... *

* Example: * *


     *   doThrow(new RuntimeException()).when(mock).someVoidMethod();
     * 
* * @param toBeThrown to be thrown when the stubbed method is called * @return stubber - to select a method for stubbing */ public static Stubber doThrow(Throwable... toBeThrown) { return MOCKITO_CORE.stubber().doThrow(toBeThrown); } /** * Use doThrow() when you want to stub the void method with an exception. *

* A new exception instance will be created for each method invocation. *

* Stubbing voids requires different approach from {@link Mockito#when(Object)} because the compiler * does not like void methods inside brackets... *

* Example: * *


     *   doThrow(RuntimeException.class).when(mock).someVoidMethod();
     * 
* * @param toBeThrown to be thrown when the stubbed method is called * @return stubber - to select a method for stubbing * @since 2.1.0 */ public static Stubber doThrow(Class toBeThrown) { return MOCKITO_CORE.stubber().doThrow(toBeThrown); } /** * Same as {@link #doThrow(Class)} but sets consecutive exception classes to be thrown. Remember to use * doThrow() when you want to stub the void method to throw several exceptions * that are instances of the specified class. *

* A new exception instance will be created for each method invocation. *

* Stubbing voids requires different approach from {@link Mockito#when(Object)} because the compiler * does not like void methods inside brackets... *

* Example: * *


     *   doThrow(RuntimeException.class, BigFailure.class).when(mock).someVoidMethod();
     * 
* * @param toBeThrown to be thrown when the stubbed method is called * @param toBeThrownNext next to be thrown when the stubbed method is called * @return stubber - to select a method for stubbing * @since 2.1.0 */ // Additional method helps users of JDK7+ to hide heap pollution / unchecked generics array // creation @SuppressWarnings({"unchecked", "varargs"}) public static Stubber doThrow( Class toBeThrown, Class... toBeThrownNext) { return MOCKITO_CORE.stubber().doThrow(toBeThrown, toBeThrownNext); } /** * Use doCallRealMethod() when you want to call the real implementation of a method. *

* As usual, you are going to read the partial mock warning: * Object oriented programming is more-or-less tackling complexity by dividing the complexity into separate, specific, SRPy objects. * How does partial mock fit into this paradigm? Well, it just doesn't... * Partial mock usually means that the complexity has been moved to a different method on the same object. * In most cases, this is not the way you want to design your application. *

* However, there are rare cases when partial mocks come handy: * dealing with code you cannot change easily (3rd party interfaces, interim refactoring of legacy code etc.) * However, I wouldn't use partial mocks for new, test-driven and well-designed code. *

* See also javadoc {@link Mockito#spy(Object)} to find out more about partial mocks. * Mockito.spy() is a recommended way of creating partial mocks. * The reason is it guarantees real methods are called against correctly constructed object because you're responsible for constructing the object passed to spy() method. *

* Example: *


     *   Foo mock = mock(Foo.class);
     *   doCallRealMethod().when(mock).someVoidMethod();
     *
     *   // this will call the real implementation of Foo.someVoidMethod()
     *   mock.someVoidMethod();
     * 
*

* See examples in javadoc for {@link Mockito} class * * @return stubber - to select a method for stubbing * @since 1.9.5 */ public static Stubber doCallRealMethod() { return MOCKITO_CORE.stubber().doCallRealMethod(); } /** * Use doAnswer() when you want to stub a void method with generic {@link Answer}. *

* Stubbing voids requires different approach from {@link Mockito#when(Object)} because the compiler does not like void methods inside brackets... *

* Example: * *


     *  doAnswer(new Answer() {
     *      public Object answer(InvocationOnMock invocation) {
     *          Object[] args = invocation.getArguments();
     *          Mock mock = invocation.getMock();
     *          return null;
     *      }})
     *  .when(mock).someMethod();
     * 
*

* See examples in javadoc for {@link Mockito} class * * @param answer to answer when the stubbed method is called * @return stubber - to select a method for stubbing */ public static Stubber doAnswer(Answer answer) { return MOCKITO_CORE.stubber().doAnswer(answer); } /** * Use doNothing() for setting void methods to do nothing. Beware that void methods on mocks do nothing by default! * However, there are rare situations when doNothing() comes handy: *

*

    *
  1. Stubbing consecutive calls on a void method: *
    
         *   doNothing().
         *   doThrow(new RuntimeException())
         *   .when(mock).someVoidMethod();
         *
         *   //does nothing the first time:
         *   mock.someVoidMethod();
         *
         *   //throws RuntimeException the next time:
         *   mock.someVoidMethod();
         * 
    *
  2. *
  3. When you spy real objects and you want the void method to do nothing: *
    
         *   List list = new LinkedList();
         *   List spy = spy(list);
         *
         *   //let's make clear() do nothing
         *   doNothing().when(spy).clear();
         *
         *   spy.add("one");
         *
         *   //clear() does nothing, so the list still contains "one"
         *   spy.clear();
         * 
    *
  4. *
*

* See examples in javadoc for {@link Mockito} class * * @return stubber - to select a method for stubbing */ public static Stubber doNothing() { return MOCKITO_CORE.stubber().doNothing(); } /** * Use doReturn() in those rare occasions when you cannot use {@link Mockito#when(Object)}. *

* Beware that {@link Mockito#when(Object)} is always recommended for stubbing because it is argument type-safe * and more readable (especially when stubbing consecutive calls). *

* Here are those rare occasions when doReturn() comes handy: *

* *

    *
  1. When spying real objects and calling real methods on a spy brings side effects * *
    
         *   List list = new LinkedList();
         *   List spy = spy(list);
         *
         *   //Impossible: real method is called so spy.get(0) throws IndexOutOfBoundsException (the list is yet empty)
         *   when(spy.get(0)).thenReturn("foo");
         *
         *   //You have to use doReturn() for stubbing:
         *   doReturn("foo").when(spy).get(0);
         * 
    *
  2. * *
  3. Overriding a previous exception-stubbing: *
    
         *   when(mock.foo()).thenThrow(new RuntimeException());
         *
         *   //Impossible: the exception-stubbed foo() method is called so RuntimeException is thrown.
         *   when(mock.foo()).thenReturn("bar");
         *
         *   //You have to use doReturn() for stubbing:
         *   doReturn("bar").when(mock).foo();
         * 
    *
  4. *
* * Above scenarios shows a tradeoff of Mockito's elegant syntax. Note that the scenarios are very rare, though. * Spying should be sporadic and overriding exception-stubbing is very rare. Not to mention that in general * overriding stubbing is a potential code smell that points out too much stubbing. *

* See examples in javadoc for {@link Mockito} class * * @param toBeReturned to be returned when the stubbed method is called * @return stubber - to select a method for stubbing */ public static Stubber doReturn(Object toBeReturned) { return MOCKITO_CORE.stubber().doReturn(toBeReturned); } /** * Same as {@link #doReturn(Object)} but sets consecutive values to be returned. Remember to use * doReturn() in those rare occasions when you cannot use {@link Mockito#when(Object)}. *

* Beware that {@link Mockito#when(Object)} is always recommended for stubbing because it is argument type-safe * and more readable (especially when stubbing consecutive calls). *

* Here are those rare occasions when doReturn() comes handy: *

* *

    *
  1. When spying real objects and calling real methods on a spy brings side effects * *
    
         *   List list = new LinkedList();
         *   List spy = spy(list);
         *
         *   //Impossible: real method is called so spy.get(0) throws IndexOutOfBoundsException (the list is yet empty)
         *   when(spy.get(0)).thenReturn("foo", "bar", "qix");
         *
         *   //You have to use doReturn() for stubbing:
         *   doReturn("foo", "bar", "qix").when(spy).get(0);
         * 
    *
  2. * *
  3. Overriding a previous exception-stubbing: *
    
         *   when(mock.foo()).thenThrow(new RuntimeException());
         *
         *   //Impossible: the exception-stubbed foo() method is called so RuntimeException is thrown.
         *   when(mock.foo()).thenReturn("bar", "foo", "qix");
         *
         *   //You have to use doReturn() for stubbing:
         *   doReturn("bar", "foo", "qix").when(mock).foo();
         * 
    *
  4. *
* * Above scenarios shows a trade-off of Mockito's elegant syntax. Note that the scenarios are very rare, though. * Spying should be sporadic and overriding exception-stubbing is very rare. Not to mention that in general * overriding stubbing is a potential code smell that points out too much stubbing. *

* See examples in javadoc for {@link Mockito} class * * @param toBeReturned to be returned when the stubbed method is called * @param toBeReturnedNext to be returned in consecutive calls when the stubbed method is called * @return stubber - to select a method for stubbing * @since 2.1.0 */ @SuppressWarnings({"unchecked", "varargs"}) public static Stubber doReturn(Object toBeReturned, Object... toBeReturnedNext) { return MOCKITO_CORE.stubber().doReturn(toBeReturned, toBeReturnedNext); } /** * Creates {@link org.mockito.InOrder} object that allows verifying mocks in order. * *


     *   InOrder inOrder = inOrder(firstMock, secondMock);
     *
     *   inOrder.verify(firstMock).add("was called first");
     *   inOrder.verify(secondMock).add("was called second");
     * 
* * Verification in order is flexible - you don't have to verify all interactions one-by-one * but only those that you are interested in testing in order. *

* Also, you can create InOrder object passing only mocks that are relevant for in-order verification. *

* InOrder verification is 'greedy', but you will hardly ever notice it. * If you want to find out more, read * this wiki page. *

* As of Mockito 1.8.4 you can verifyNoMoreInteractions() in order-sensitive way. Read more: {@link InOrder#verifyNoMoreInteractions()} *

* See examples in javadoc for {@link Mockito} class * * @param mocks to be verified in order * * @return InOrder object to be used to verify in order */ public static InOrder inOrder(Object... mocks) { return MOCKITO_CORE.inOrder(mocks); } /** * Ignores stubbed methods of given mocks for the sake of verification. * Please consider using {@link Strictness#STRICT_STUBS} feature which eliminates the need for ignoreStubs() * and provides other benefits. *

* ignoreStubs() is sometimes useful when coupled with verifyNoMoreInteractions() or verification inOrder(). * Helps to avoid redundant verification of stubbed calls - typically we're not interested in verifying stubs. *

* Warning, ignoreStubs() might lead to overuse of verifyNoMoreInteractions(ignoreStubs(...)); * Bear in mind that Mockito does not recommend bombarding every test with verifyNoMoreInteractions() * for the reasons outlined in javadoc for {@link Mockito#verifyNoMoreInteractions(Object...)} * Other words: all *stubbed* methods of given mocks are marked *verified* so that they don't get in a way during verifyNoMoreInteractions(). *

* This method changes the input mocks! This method returns input mocks just for convenience. *

* Ignored stubs will also be ignored for verification inOrder, including {@link org.mockito.InOrder#verifyNoMoreInteractions()}. * See the second example. *

* Example: *


     *  //mocking lists for the sake of the example (if you mock List in real you will burn in hell)
     *  List mock1 = mock(List.class), mock2 = mock(List.class);
     *
     *  //stubbing mocks:
     *  when(mock1.get(0)).thenReturn(10);
     *  when(mock2.get(0)).thenReturn(20);
     *
     *  //using mocks by calling stubbed get(0) methods:
     *  System.out.println(mock1.get(0)); //prints 10
     *  System.out.println(mock2.get(0)); //prints 20
     *
     *  //using mocks by calling clear() methods:
     *  mock1.clear();
     *  mock2.clear();
     *
     *  //verification:
     *  verify(mock1).clear();
     *  verify(mock2).clear();
     *
     *  //verifyNoMoreInteractions() fails because get() methods were not accounted for.
     *  try { verifyNoMoreInteractions(mock1, mock2); } catch (NoInteractionsWanted e);
     *
     *  //However, if we ignore stubbed methods then we can verifyNoMoreInteractions()
     *  verifyNoMoreInteractions(ignoreStubs(mock1, mock2));
     *
     *  //Remember that ignoreStubs() *changes* the input mocks and returns them for convenience.
     * 
* Ignoring stubs can be used with verification in order: *

     *  List list = mock(List.class);
     *  when(list.get(0)).thenReturn("foo");
     *
     *  list.add(0);
     *  list.clear();
     *  System.out.println(list.get(0)); //we don't want to verify this
     *
     *  InOrder inOrder = inOrder(ignoreStubs(list));
     *  inOrder.verify(list).add(0);
     *  inOrder.verify(list).clear();
     *  inOrder.verifyNoMoreInteractions();
     * 
* Stubbed invocations are automatically verified with {@link Strictness#STRICT_STUBS} feature * and it eliminates the need for ignoreStubs(). Example below uses JUnit Rules: *

     *  @Rule public MockitoRule mockito = MockitoJUnit.rule().strictness(Strictness.STRICT_STUBS);
     *
     *  List list = mock(List.class);
     *  when(list.get(0)).thenReturn("foo");
     *
     *  list.size();
     *  verify(list).size();
     *
     *  list.get(0); // Automatically verified by STRICT_STUBS
     *  verifyNoMoreInteractions(list); // No need of ignoreStubs()
     * 
* * @since 1.9.0 * @param mocks input mocks that will be changed * @return the same mocks that were passed in as parameters */ public static Object[] ignoreStubs(Object... mocks) { return MOCKITO_CORE.ignoreStubs(mocks); } /** * Allows verifying exact number of invocations. E.g: *

     *   verify(mock, times(2)).someMethod("some arg");
     * 
* * See examples in javadoc for {@link Mockito} class * * @param wantedNumberOfInvocations wanted number of invocations * * @return verification mode */ public static VerificationMode times(int wantedNumberOfInvocations) { return VerificationModeFactory.times(wantedNumberOfInvocations); } /** * Alias to times(0), see {@link Mockito#times(int)} *

* Verifies that interaction did not happen. E.g: *


     *   verify(mock, never()).someMethod();
     * 
* *

* If you want to verify there were NO interactions with the mock * check out {@link Mockito#verifyNoMoreInteractions(Object...)} *

* See examples in javadoc for {@link Mockito} class * * @return verification mode */ public static VerificationMode never() { return times(0); } /** * Allows at-least-once verification. E.g: *


     *   verify(mock, atLeastOnce()).someMethod("some arg");
     * 
* Alias to atLeast(1). *

* See examples in javadoc for {@link Mockito} class * * @return verification mode */ public static VerificationMode atLeastOnce() { return VerificationModeFactory.atLeastOnce(); } /** * Allows at-least-x verification. E.g: *


     *   verify(mock, atLeast(3)).someMethod("some arg");
     * 
* * See examples in javadoc for {@link Mockito} class * * @param minNumberOfInvocations minimum number of invocations * * @return verification mode */ public static VerificationMode atLeast(int minNumberOfInvocations) { return VerificationModeFactory.atLeast(minNumberOfInvocations); } /** * Allows at-most-once verification. E.g: *

     *   verify(mock, atMostOnce()).someMethod("some arg");
     * 
* Alias to atMost(1). *

* See examples in javadoc for {@link Mockito} class * * @return verification mode */ public static VerificationMode atMostOnce() { return VerificationModeFactory.atMostOnce(); } /** * Allows at-most-x verification. E.g: *


     *   verify(mock, atMost(3)).someMethod("some arg");
     * 
* * See examples in javadoc for {@link Mockito} class * * @param maxNumberOfInvocations max number of invocations * * @return verification mode */ public static VerificationMode atMost(int maxNumberOfInvocations) { return VerificationModeFactory.atMost(maxNumberOfInvocations); } /** * Allows non-greedy verification in order. For example *

     *   inOrder.verify( mock, calls( 2 )).someMethod( "some arg" );
     * 
*
    *
  • will not fail if the method is called 3 times, unlike times( 2 )
  • *
  • will not mark the third invocation as verified, unlike atLeast( 2 )
  • *
* This verification mode can only be used with in order verification. * @param wantedNumberOfInvocations number of invocations to verify * @return verification mode */ public static VerificationMode calls(int wantedNumberOfInvocations) { return VerificationModeFactory.calls(wantedNumberOfInvocations); } /** * Allows checking if given method was the only one invoked. E.g: *

     *   verify(mock, only()).someMethod();
     *   //above is a shorthand for following 2 lines of code:
     *   verify(mock).someMethod();
     *   verifyNoMoreInteractions(mock);
     * 
* *

* See also {@link Mockito#verifyNoMoreInteractions(Object...)} *

* See examples in javadoc for {@link Mockito} class * * @return verification mode */ public static VerificationMode only() { return VerificationModeFactory.only(); } /** * Verification will be triggered over and over until the given amount of millis, allowing testing of async code. * Useful when interactions with the mock object did not happened yet. * Extensive use of {@code timeout()} method can be a code smell - there are better ways of testing concurrent code. *

* See also {@link #after(long)} method for testing async code. * Differences between {@code timeout()} and {@code after} are explained in Javadoc for {@link #after(long)}. * *


     *   //passes when someMethod() is called no later than within 100 ms
     *   //exits immediately when verification is satisfied (e.g. may not wait full 100 ms)
     *   verify(mock, timeout(100)).someMethod();
     *   //above is an alias to:
     *   verify(mock, timeout(100).times(1)).someMethod();
     *
     *   //passes as soon as someMethod() has been called 2 times under 100 ms
     *   verify(mock, timeout(100).times(2)).someMethod();
     *
     *   //equivalent: this also passes as soon as someMethod() has been called 2 times under 100 ms
     *   verify(mock, timeout(100).atLeast(2)).someMethod();
     * 
* * See examples in javadoc for {@link Mockito} class * * @param millis - duration in milliseconds * * @return object that allows fluent specification of the verification (times(x), atLeast(y), etc.) */ public static VerificationWithTimeout timeout(long millis) { return new Timeout(millis, VerificationModeFactory.times(1)); } /** * Verification will be triggered after given amount of millis, allowing testing of async code. * Useful when interactions with the mock object have yet to occur. * Extensive use of {@code after()} method can be a code smell - there are better ways of testing concurrent code. *

* Not yet implemented to work with InOrder verification. *

* See also {@link #timeout(long)} method for testing async code. * Differences between {@code timeout()} and {@code after()} are explained below. * *


     *   //passes after 100ms, if someMethod() has only been called once at that time.
     *   verify(mock, after(100)).someMethod();
     *   //above is an alias to:
     *   verify(mock, after(100).times(1)).someMethod();
     *
     *   //passes if someMethod() is called *exactly* 2 times, as tested after 100 millis
     *   verify(mock, after(100).times(2)).someMethod();
     *
     *   //passes if someMethod() has not been called, as tested after 100 millis
     *   verify(mock, after(100).never()).someMethod();
     *
     *   //verifies someMethod() after a given time span using given verification mode
     *   //useful only if you have your own custom verification modes.
     *   verify(mock, new After(100, yourOwnVerificationMode)).someMethod();
     * 
* * timeout() vs. after() *
    *
  • timeout() exits immediately with success when verification passes
  • *
  • after() awaits full duration to check if verification passes
  • *
* Examples: *

     *   //1.
     *   mock.foo();
     *   verify(mock, after(1000)).foo();
     *   //waits 1000 millis and succeeds
     *
     *   //2.
     *   mock.foo();
     *   verify(mock, timeout(1000)).foo();
     *   //succeeds immediately
     * 
* * See examples in javadoc for {@link Mockito} class * * @param millis - duration in milliseconds * * @return object that allows fluent specification of the verification */ public static VerificationAfterDelay after(long millis) { return new After(millis, VerificationModeFactory.times(1)); } /** * First of all, in case of any trouble, I encourage you to read the Mockito FAQ: https://github.com/mockito/mockito/wiki/FAQ *

* In case of questions you may also post to mockito mailing list: https://groups.google.com/group/mockito *

* validateMockitoUsage() explicitly validates the framework state to detect invalid use of Mockito. * However, this feature is optional because Mockito validates the usage all the time... but there is a gotcha so read on. *

* Examples of incorrect use: *


     * //Oops, thenReturn() part is missing:
     * when(mock.get());
     *
     * //Oops, verified method call is inside verify() where it should be on the outside:
     * verify(mock.execute());
     *
     * //Oops, missing method to verify:
     * verify(mock);
     * 
* * Mockito throws exceptions if you misuse it so that you know if your tests are written correctly. * The gotcha is that Mockito does the validation next time you use the framework (e.g. next time you verify, stub, call mock etc.). * But even though the exception might be thrown in the next test, * the exception message contains a navigable stack trace element with location of the defect. * Hence you can click and find the place where Mockito was misused. *

* Sometimes though, you might want to validate the framework usage explicitly. * For example, one of the users wanted to put validateMockitoUsage() in his @After method * so that he knows immediately when he misused Mockito. * Without it, he would have known about it not sooner than next time he used the framework. * One more benefit of having validateMockitoUsage() in @After is that jUnit runner and rule will always fail in the test method with defect * whereas ordinary 'next-time' validation might fail the next test method. * But even though JUnit might report next test as red, don't worry about it * and just click at navigable stack trace element in the exception message to instantly locate the place where you misused mockito. *

* Both built-in runner: {@link MockitoJUnitRunner} and rule: {@link MockitoRule} do validateMockitoUsage() after each test method. *

* Bear in mind that usually you don't have to validateMockitoUsage() * and framework validation triggered on next-time basis should be just enough, * mainly because of enhanced exception message with clickable location of defect. * However, I would recommend validateMockitoUsage() if you already have sufficient test infrastructure * (like your own runner or base class for all tests) because adding a special action to @After has zero cost. *

* See examples in javadoc for {@link Mockito} class */ public static void validateMockitoUsage() { MOCKITO_CORE.validateMockitoUsage(); } /** * Allows mock creation with additional mock settings. *

* Don't use it too often. * Consider writing simple tests that use simple mocks. * Repeat after me: simple tests push simple, KISSy, readable and maintainable code. * If you cannot write a test in a simple way - refactor the code under test. *

* Examples of mock settings: *


     *   //Creates mock with different default answer and name
     *   Foo mock = mock(Foo.class, withSettings()
     *       .defaultAnswer(RETURNS_SMART_NULLS)
     *       .name("cool mockie"));
     *
     *   //Creates mock with different default answer, descriptive name and extra interfaces
     *   Foo mock = mock(Foo.class, withSettings()
     *       .defaultAnswer(RETURNS_SMART_NULLS)
     *       .name("cool mockie")
     *       .extraInterfaces(Bar.class));
     * 
* {@link MockSettings} has been introduced for two reasons. * Firstly, to make it easy to add another mock settings when the demand comes. * Secondly, to enable combining different mock settings without introducing zillions of overloaded mock() methods. *

* See javadoc for {@link MockSettings} to learn about possible mock settings. *

* * @return mock settings instance with defaults. */ public static MockSettings withSettings() { return new MockSettingsImpl().defaultAnswer(RETURNS_DEFAULTS); } /** * Adds a description to be printed if verification fails. *


     * verify(mock, description("This will print on failure")).someMethod("some arg");
     * 
* @param description The description to print on failure. * @return verification mode * @since 2.1.0 */ public static VerificationMode description(String description) { return times(1).description(description); } /** * For advanced users or framework integrators. See {@link MockitoFramework} class. * * @since 2.1.0 */ public static MockitoFramework framework() { return new DefaultMockitoFramework(); } /** * {@code MockitoSession} is an optional, highly recommended feature * that drives writing cleaner tests by eliminating boilerplate code and adding extra validation. *

* For more information, including use cases and sample code, see the javadoc for {@link MockitoSession}. * * @since 2.7.0 */ public static MockitoSessionBuilder mockitoSession() { return new DefaultMockitoSessionBuilder(); } /** * Lenient stubs bypass "strict stubbing" validation (see {@link Strictness#STRICT_STUBS}). * When stubbing is declared as lenient, it will not be checked for potential stubbing problems such as * 'unnecessary stubbing' ({@link UnnecessaryStubbingException}) or for 'stubbing argument mismatch' {@link PotentialStubbingProblem}. * *


     *   lenient().when(mock.foo()).thenReturn("ok");
     * 
* * Most mocks in most tests don't need leniency and should happily prosper with {@link Strictness#STRICT_STUBS}. *