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JMockit is a Java toolkit for automated developer testing.
It contains mocking/faking APIs and a code coverage tool, supporting both JUnit and TestNG.
The mocking APIs allow all kinds of Java code, without testability restrictions, to be tested
in isolation from selected dependencies.
/*
* Copyright (c) 2006 Rogério Liesenfeld
* This file is subject to the terms of the MIT license (see LICENSE.txt).
*/
package mockit;
import java.util.*;
import javax.annotation.*;
import mockit.internal.expectations.*;
/**
* Used to record expectations on {@linkplain Mocked mocked} types and their instances.
*
* Each recorded expectation is intended to match one or more method or constructor invocations, that we expect will
* occur during the execution of code under test.
* When a match is detected, the recorded {@linkplain #result result} is returned to the caller.
* Alternatively, a recorded exception/error is thrown, or an arbitrary {@linkplain Delegate delegate} method is
* executed.
*
* Expectations are recorded simply by invoking the desired method or constructor on the mocked type/instance, during
* the initialization of an {@code Expectations} object.
* Typically, this is done by instantiating an anonymous subclass containing an instance initialization body, or as we
* call it, an expectation block:
*
* // Record one or more expectations on available mocked types/instances.
* new Expectations() {{
* mock1.expectedMethod(anyInt); result = 123; times = 2;
* mock2.anotherExpectedMethod(1, "test"); result = new String[] {"Abc", "xyz"};
* }};
*
* // Exercise tested code, with previously recorded expectations now available for replay.
* codeUnderTest.doSomething();
*
* Rather than creating anonymous subclasses, we can also create named subclasses to be reused in multiple
* tests.
* Some examples:
*
* public final class MyReusableExpectations extends Expectations {
* public MyReusableExpectations(...any parameters...) {
* // expectations recorded here
* }
* }
*
* public class ReusableBaseExpectations extends Expectations {
* protected ReusableBaseExpectations(...) {
* // expectations here
* }
* }
*
* @Test
* public void someTest(@Mocked final SomeType aMock, etc.) {
* // Record reusable expectations by instantiating a final "...Expectations" class.
* new MyReusableExpectations(123, "test", etc.);
*
* // Record and extend reusable expectations by instantiating a non-final base class.
* new ReusableBaseExpectations() {{
* // additional expectations
* }};
* }
*
* During replay, invocations matching a recorded expectation must occur at least once (unless specified
* otherwise);
* if, by the end of the test, no matching invocation occurred for a given recorded expectation, the test will fail with
* a {@code MissingInvocation} error.
*
* When multiple expectations are recorded, matching invocations are allowed to occur in a different order.
* So, the order in which expectations are recorded is not significant.
*
* Besides the special {@link #result} field already mentioned, there are several other fields and methods which can be
* used inside the expectation block:
* a) {@link #returns(Object, Object...)}, a convenience method for returning a sequence of values;
* b) argument matchers such as {@link #anyInt}, {@link #anyString}, {@link #withNotNull()}, etc., which relax or
* constrain the matching of argument values;
* c) the {@link #times}, {@link #minTimes}, and {@link #maxTimes} fields, which relax or constrain the expected and/or
* allowed number of matching invocations.
*
* By default, the exact instance on which instance method invocations will occur during replay is not verified
* to be the same as the instance used when recording the expectation.
* That said, instance-specific matching can be obtained by declaring the mocked type as
* {@linkplain Injectable @Injectable}, by using the {@link #onInstance(Object)} method, or by declaring multiple mock
* fields and/or mock parameters of the same mocked type (so that separate expectations can be recorded for each mock
* instance).
*
* Invocations occurring during replay, whether they matched recorded expectations or not, can be explicitly verified
* after exercising the code under test.
* To that end, we use a set of complementary base classes: {@link Verifications}, {@link VerificationsInOrder},
* {@link FullVerifications}, and {@link FullVerificationsInOrder}.
* Similar to expectation blocks, these classes allow us to create verification blocks.
*
* Finally, note that this class has two specialized subclasses: {@link StrictExpectations} and
* {@link NonStrictExpectations}.
* The first one differs in that 1) each recorded expectation has, by default, a maximum allowed number of invocations
* of {@code 1} (one); 2) matching invocations must occur in the same order as recorded; 3) only
* matching invocations are allowed, with any occurrence of unmatched invocations causing the test to fail with an
* {@code UnexpectedInvocation} error; and 4) use of verification blocks is not supported, since all invocations are
* implicitly verified through the strictly recorded sequence of expectations.
* The second one is a smaller variation, in which recorded expectations have a minimum expected number of invocations
* of {@code 0} (zero), that is, they are allowed to have no matching invocations at all by default.
* Most tests can and should only use {@code Expectations}; {@code StrictExpectations} are meant for users who prefer a
* mocking style where all expectations are specified before exercising the code under test, or for situations where
* the recording of a strict sequence of expectations produces a test that is more succinct or that fails as early as
* an unexpected invocation occurs; {@code NonStrictExpectations} are mainly useful for test setup methods
* (a {@code @Before} method in JUnit, or {@code @BeforeMethod} in TestNG), where we often end up recording expectations
* that get replayed by some tests, but not all.
*
* @see #Expectations()
* @see #Expectations(Object...)
* @see #Expectations(Integer, Object...)
* @see Tutorial
*/
public abstract class Expectations extends Invocations
{
@Nonnull private final RecordAndReplayExecution execution;
/**
* A value assigned to this field will be taken as the result for the expectation that is being recorded.
*
* If the value is a {@link Throwable} then it will be thrown when a matching invocation later occurs.
* Otherwise, it's assumed to be a return value for a non-void method, and will be returned
* from a matching invocation.
*
* If no result is recorded for a given expectation, then all matching invocations will return the appropriate
* default value according to the method return type:
*
* - Most {@code java.lang} types (
String, {@code Object}, etc.): returns {@code null}.
* - {@code java.math} types (
BigDecimal, etc.): returns {@code null}.
* - Primitive/wrapper types: returns the standard default value (
false for {@code boolean/Boolean},
* {@code 0} for {@code int/Integer}, and so on).
*
* - {@code java.util.List}, {@code java.util.Collection}, or {@code java.lang.Iterable}: returns
* {@link Collections#EMPTY_LIST}.
* - {@code java.util.Iterator} or {@code java.util.ListIterator}: returns an empty iterator.
* - {@code java.util.Set}: returns {@link Collections#EMPTY_SET}.
* - {@code java.util.SortedSet}: returns an unmodifiable empty sorted set.
* - {@code java.util.Map}: returns {@link Collections#EMPTY_MAP}.
* - {@code java.util.SortedMap}: returns an unmodifiable empty sorted map.
* - {@code java.util.Optional}: returns {@link Optional#empty()}.
* - Other reference types: returns a mocked instance through cascading.
* - Array types: returns an array with zero elements (empty) in each dimension.
*
*
* When an expectation is recorded for a method which actually returns an exception or error (as opposed to
* throwing one), then the {@link #returns(Object, Object...)} method should be used instead, as it only
* applies to return values.
*
* Assigning a value whose type differs from the method return type will cause an {@code IllegalArgumentException} to
* be thrown, unless it can be safely converted to the return type.
* One such conversion is from an array to a collection or iterator.
* Another is from an array of at least two dimensions to a map, with the first dimension providing the keys and the
* second the values.
* Yet another conversion is from a single value to a container type holding that value.
*
* A sequence of consecutive results can be recorded simply by assigning the field multiple times for the
* same expectation.
* Alternatively, the desired sequence of results for a single-valued return type can be recorded by assigning an
* array, an {@link Iterable}, or an {@link Iterator} containing the individual results in order.
*
* Results that depend on some programming logic can be provided through a {@linkplain Delegate} object assigned to
* the field.
* This applies to {@code void} and non-void methods, as well as to constructors.
*
* Finally, when recording an expectation on a constructor of a mocked class, an arbitrary instance of said
* class can be assigned to the field.
* In this case, the assigned instance will be used as a "replacement" for all invocations to
* instance methods made on other instances, provided they get created sometime later through a
* matching constructor invocation.
*
* @see #returns(Object, Object...)
* @see Tutorial
*/
protected Object result;
/**
* Registers one or more expectations recorded on available mocked types and/or mocked instances, as written inside
* the instance initialization body of an anonymous subclass or the called constructor of a named subclass.
*
* @see #Expectations(Object...)
* @see #Expectations(Integer, Object...)
*/
protected Expectations()
{
execution = new RecordAndReplayExecution(this, (Object[]) null);
}
/**
* Same as {@link #Expectations()}, except that one or more classes will be partially mocked according to the
* expectations recorded in the expectation block.
*
* The classes to be partially mocked are those directly specified through their {@code Class} objects as well as
* those to which any given objects belong.
* During replay, any invocations to one of these classes or objects will execute real production code, unless a
* matching expectation was recorded.
* This mechanism, however, does not apply to {@code native} methods, which are not supported for partial mocking.
*
* For a given {@code Class} object, all constructors and methods can be mocked, from the specified class up to but
* not including {@code java.lang.Object}.
* For a given object, only methods can be mocked, not constructors; also, during replay, invocations to
* instance methods will only match expectations recorded on the given instance (or instances, if more than one was
* given).
*
* @param classesOrObjectsToBePartiallyMocked one or more classes or objects whose classes are to be partially mocked
*
* @throws IllegalArgumentException if given a class literal for an interface, an annotation, an array, a
* primitive/wrapper type, or a {@linkplain java.lang.reflect.Proxy#isProxyClass(Class) proxy class} created for an
* interface, or if given a value/instance of such a type
*
* @see #Expectations(Integer, Object...)
* @see Tutorial
*/
protected Expectations(Object... classesOrObjectsToBePartiallyMocked)
{
execution = new RecordAndReplayExecution(this, classesOrObjectsToBePartiallyMocked);
}
/**
* Same as {@link #Expectations(Object...)}, but considering that the invocations inside the block will occur in a
* given number of iterations.
*
* The effect of specifying a number of iterations larger than 1 (one) is equivalent to multiplying by that number
* the lower and upper invocation count limits for each invocation inside the expectation block.
*
* It's also valid to have multiple expectation blocks for the same test, each with an arbitrary number of
* iterations.
*
* @param numberOfIterations the positive number of iterations for the whole set of expectations recorded inside the
* block; when not specified, 1 (one) iteration is assumed
* @param classesOrObjectsToBePartiallyMocked one or more classes or objects whose classes are to be partially mocked
*
* @see #Expectations()
* @see Tutorial
*/
protected Expectations(Integer numberOfIterations, Object... classesOrObjectsToBePartiallyMocked)
{
this(classesOrObjectsToBePartiallyMocked);
getCurrentPhase().setNumberOfIterations(numberOfIterations);
}
@Nonnull @Override
final RecordPhase getCurrentPhase() { return execution.getRecordPhase(); }
/**
* Specifies that the previously recorded method invocation will return a given sequence of values during replay.
*
* Calling this method is equivalent to assigning the {@link #result} field two or more times in sequence, or
* assigning it a single time with an array or iterable containing the same sequence of values.
*
* Certain data conversions will be applied, depending on the return type of the recorded method:
*
* - If the return type is iterable and can receive a {@link List} value, then the given sequence of values will be
* converted into an {@code ArrayList}; this list will then be returned by matching invocations at replay time.
* - If the return type is {@code SortedSet} or a sub-type, then the given sequence of values will be converted
* into a {@code TreeSet}; otherwise, if it is {@code Set} or a sub-type, then a {@code LinkedHashSet} will be
* created to hold the values; the set will then be returned by matching invocations at replay time.
* - If the return type is {@code Iterator} or a sub-type, then the given sequence of values will be converted into
* a {@code List} and the iterator created from this list will be returned by matching invocations at replay
* time.
* - If the return type is an array, then the given sequence of values will be converted to an array of the same
* type, which will be returned by matching invocations at replay time.
*
* The current expectation will have its upper invocation count automatically set to the total number of values
* specified to be returned.
* This upper limit can be overridden through the {@code maxTimes} field, if necessary.
*
* If this method is used for a constructor or {@code void} method, the given return values will be ignored,
* but matching invocations will be allowed during replay; they will simply do nothing.
*
* @param firstValue the first value to be returned at replay time
* @param remainingValues the remaining values to be returned, in the same order
*
* @see Tutorial
*/
protected final void returns(Object firstValue, Object... remainingValues)
{
getCurrentPhase().addSequenceOfReturnValues(firstValue, remainingValues);
}
}