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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 JMockit developers
* 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
* Expectations object.
* 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 = "Abc";
* }};
*
* // Exercise tested code, with previously recorded expectations now available for replay.
* codeUnderTest.doSomething();
*
* 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
* 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, 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}, 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}, and {@link FullVerifications}.
* Similar to expectation blocks, these classes allow us to create verification blocks.
*
* @see #Expectations()
* @see #Expectations(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 java.lang types (String, Object, etc.): returns null.
* - java.math types (BigDecimal, etc.): returns null.
* - Primitive/wrapper types: returns the standard default value (
false for boolean/Boolean, 0 for
* int/Integer, and so on).
*
* - java.util.List, java.util.Collection, or java.lang.Iterable: returns
* {@link Collections#EMPTY_LIST}.
* - java.util.Iterator or java.util.ListIterator: returns an empty iterator.
* - java.util.Set: returns {@link Collections#EMPTY_SET}.
* - java.util.SortedSet: returns an unmodifiable empty sorted set.
* - java.util.Map: returns {@link Collections#EMPTY_MAP}.
* - java.util.SortedMap: returns an unmodifiable empty sorted map.
* - 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, 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 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 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, additional expectations recorded or verified on the assigned instance will also match invocations to instance methods
* made on future instances, provided they get created through a matching constructor invocation.
*
* @see #returns(Object, Object, Object...)
* @see Tutorial
*/
@Nullable
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.
*
* @see #Expectations(Object...)
* @see Tutorial
*/
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 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 native methods, which are not supported for partial mocking.
*
* For a given Class object, all constructors and methods can be mocked, from the specified class up to but not including
* 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 object for an interface, an annotation, an array, a primitive/wrapper type, a
* synthetic class, a {@linkplain java.lang.reflect.Proxy#isProxyClass(Class) proxy class}, or if given a value/instance of such a type
*
* @see Tutorial
*/
protected Expectations(@Nonnull Object... classesOrObjectsToBePartiallyMocked) {
execution = new RecordAndReplayExecution(this, classesOrObjectsToBePartiallyMocked);
}
@Nullable @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
* ArrayList; this list will then be returned by matching invocations at replay time.
* - If the return type is SortedSet or a sub-type, then the given sequence of values will be converted into a
* TreeSet; otherwise, if it is Set or a sub-type, then a 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 Iterator or a sub-type, then the given sequence of values will be converted into a 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 maxTimes field, if necessary.
*
* @param firstValue the first value to be returned at replay time
* @param secondValue the second value to be returned at replay time
* @param remainingValues any remaining values to be returned, in the same order
*
* @see Tutorial
*/
protected final void returns(@Nullable Object firstValue, @Nullable Object secondValue, @Nonnull Object... remainingValues) {
RecordPhase currentPhase = getCurrentPhase();
if (currentPhase != null) {
int n = remainingValues.length;
Object[] values = new Object[2 + n];
values[0] = firstValue;
values[1] = secondValue;
System.arraycopy(remainingValues, 0, values, 2, n);
currentPhase.addSequenceOfReturnValues(values);
}
}
}