Package mockit

Annotation Type Mocked

@Retention(RUNTIME) @Target({FIELD,PARAMETER}) public @interface Mocked
Indicates an instance field of a test class as being a mock field, or a parameter of a test method as a mock parameter; in either case, the declared type of the field/parameter is a mocked type, whose instances are mocked instances.

Mocked types can also be introduced by other annotations: @Injectable, @Capturing. Their effect is to constrain or extend the mocking capabilities here specified.

Any type can be mocked, except for primitive and array types. A mocked instance of that type is automatically created and assigned to the mock field/parameter, for use when recording and/or verifying expectations. For a mock field, the test itself can provide the instance by declaring the field as final and assigning it the desired instance (or null).

The effect of declaring a @Mocked type, by default, is that all new instances of that type, as well as those previously created, will also be mocked instances; this will last for the duration of each test where the associated mock field/parameter is in scope. All non-private methods of the mocked type will be mocked.

When the mocked type is a class, all super-classes up to but not including java.lang.Object are also mocked. Additionally, static methods and constructors are mocked as well, just like instance methods; native methods are also mocked, provided they are public or protected.

While a method or constructor is mocked, an invocation does not result in the execution of the original code, but in a (generated) call into JMockit, which then responds with either a default or a recorded result (or with a constraint violation, if the invocation is deemed to be unexpected).

Mocking will automatically cascade into the return types of all non-void methods belonging to the mocked type, except for non-eligible ones (primitive wrappers, String, and collections/maps). When needed, such cascaded returns can be overridden by explicitly recording a return value for the mocked method. If there is a mock field/parameter with the same type (or a subtype) of some cascaded type, then the original instance from that mock field/parameter will be used as the cascaded instance, rather than a new one being created; this applies to all cascading levels, and even to the type of the mock field/parameter itself (ie, if a method in class/interface "A" has return type A, then it will return itself by default). Finally, when new cascaded instances are created, @Injectable semantics apply.

Static class initializers (including assignments to static fields) of a mocked class are not affected, unless specified otherwise.

See Also:

  • Optional Element Summary

    Optional Elements
    Modifier and Type
    Optional Element
    Description
    boolean
    stubOutClassInitialization
    Indicates whether static initialization code in the mocked class should be stubbed out or not.

  • Element Details

    • stubOutClassInitialization

      boolean stubOutClassInitialization
      Indicates whether static initialization code in the mocked class should be stubbed out or not. Static initialization includes the execution of assignments to static fields of the class and the execution of static initialization blocks, if any. (Note that static final fields initialized with compile-time constants are not assigned at runtime, remaining unaffected whether the class is stubbed out or not.)

      By default, static initialization code in a mocked class is not stubbed out. The JVM will only perform static initialization of a class once, so stubbing out the initialization code can have unexpected consequences. Stubbing out the static initialization of a class is an unsafe operation, which can cause other tests, executed later in the same test run, to unexpectedly fail; instead of resorting to stubbing out a class's static initializer, the root cause for wanting to stub it out should be eliminated. Caveat Emptor.

      Returns:
      true, if successful
      Default:
      false