mockit.Mock Maven / Gradle / Ivy

/*
 * Copyright (c) 2006-2013 Rogério Liesenfeld
 * This file is subject to the terms of the MIT license (see LICENSE.txt).
 */
package mockit;

import java.lang.annotation.*;

/**
 * Used inside a mock class to indicate a mock method whose implementation will temporarily replace
 * the implementation of a matching "real" method.
 * 
 * The mock method must have the same name and the same parameters as the matching real method, except for an optional
 * first parameter of type {@link Invocation}; if this extra parameter is present, the remaining ones must match the
 * parameters in the real method.
 * The mock method must also have the same return type as the matching real method.
 * 

 * Method modifiers (including public, final, and even static), however,
 * don't have to be the same.
 * Checked exceptions in the throws clause (if any) can also differ between the two matching methods.
 * A mock method can also target a constructor, in which case the previous considerations still apply,
 * except for the name of the mock method which must be "$init".
 * 

 * A mock method can specify constraints on the number of invocations it should receive while in effect
 * (ie, from the time a real method/constructor is mocked to the time it is restored to its original definition).
 * 

 * The special mock methods {@code void $init(...)} and {@code void $clinit()}
 * correspond to constructors and to {@code static} class initializers, respectively.
 * (Notice that it makes no difference if the real class contains more than one static initialization block, because the
 * compiler merges the sequence of static blocks into a single internal "<clinit>" static method in the class file.)
 * Mock methods named {@code $init} will apply to the corresponding constructor in the real class, by matching the
 * declared parameters; just like regular mock methods, they can also have a first parameter of type {@link Invocation}.
 * 

 * In the Tutorial
 *
 * @see #invocations invocations
 * @see #minInvocations minInvocations
 * @see #maxInvocations maxInvocations
 * @see #reentrant reentrant
 * @see MockUp
 */
@Inherited
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Mock
{
   /**
    * Number of expected invocations of the mock method.
    * If 0 (zero), no invocations will be expected.
    * A negative value (the default) means there is no expectation on the number of invocations;
    * that is, the mock can be called any number of times or not at all during any test which uses it.
    * 

    * A non-negative value is equivalent to setting {@link #minInvocations minInvocations} and
    * {@link #maxInvocations maxInvocations} to that same value.
    */
   int invocations() default -1;

   /**
    * Minimum number of expected invocations of the mock method, starting from 0 (zero, which is the default).
    * 
    * @see #invocations invocations
    * @see #maxInvocations maxInvocations
    */
   int minInvocations() default 0;

   /**
    * Maximum number of expected invocations of the mock method, if positive.
    * If zero the mock is not expected to be called at all.
    * A negative value (the default) means there is no expectation on the maximum number of invocations.
    * 
    * @see #invocations invocations
    * @see #minInvocations minInvocations
    */
   int maxInvocations() default -1;

   /**
    * Indicates whether or not the mock method implementation is allowed to call the corresponding real method on the
    * {@code it} field before it returns from an execution.
    * (The {@code it} field is an instance field defined in the mock class with name "it" and of the same type as the
    * mocked class, which will be set to the real class instance for each indirect call to a mock method.)
    * By default, such reentrant calls are not allowed because they lead to infinite recursion, with the mock method
    * calling itself indirectly through the mocked method.
    * 

    * When allowed to make such calls, the mock method effectively behaves as advice to the corresponding real
    * method.
    * 
    * As an alternative, consider adding a first parameter of type {@link Invocation} to the mock method, making it
    * automatically reentrant.
    *
    * @deprecated This attribute will be removed in a future release.
    * Existing mock methods marked as reentrant should instead have an {@link Invocation} parameter.
    * Uses of the "it" field should be replaced with calls to corresponding methods in the
    * {@code Invocation} object, in particular {@link Invocation#getInvokedInstance()} to obtain the "it" instance, and
    * {@link Invocation#proceed(...)} to execute the real method.
    */
   @Deprecated
   boolean reentrant() default false;
}