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`@MockitoBean` and `@MockitoSpyBean`

@MockitoBean and @MockitoSpyBean are used on fields in test classes to override beans in the test’s ApplicationContext with a Mockito mock or spy, respectively. In the latter case, the original bean definition is not replaced, but instead an early instance of the bean is captured and wrapped by the spy.

By default, the annotated field’s type is used to search for candidate bean definitions to override. If multiple candidates match, @Qualifier can be provided to narrow the candidate to override. Alternatively, a candidate whose bean definition name matches the name of the field will match.

To use a by-name override rather than a by-type override, specify the name attribute of the annotation.

Qualifiers, including the name of the field, are used to determine if a separate ApplicationContext needs to be created. If you are using this feature to mock or spy the same bean in several tests, make sure to name the field consistently to avoid creating unnecessary contexts.

Each annotation also defines Mockito-specific attributes to fine-tune the mocking details.

The @MockitoBean annotation uses the REPLACE_OR_CREATE_DEFINITION strategy for test bean overriding. If no existing bean definition matches, a new bean definition is created on the fly.

The @MockitoSpyBean annotation uses the WRAP_BEAN strategy, and the original instance is wrapped in a Mockito spy. This strategy requires that exactly one candidate bean definition exists.

The following example shows how to use the default behavior of the @MockitoBean annotation:

Java

class OverrideBeanTests {
	@MockitoBean (1)
	private CustomService customService;

	// test case body...
}

1	Replace the bean with type `CustomService` with a Mockito `mock`.

In the example above, we are creating a mock for CustomService. If more than one bean of that type exists, the bean named customService is considered. Otherwise, the test will fail, and you will need to provide a qualifier of some sort to identify which of the CustomService beans you want to override. If no such bean exists, a bean definition will be created with an auto-generated bean name.

The following example uses a by-name lookup, rather than a by-type lookup:

Java

class OverrideBeanTests {
	@MockitoBean(name = "service") (1)
	private CustomService customService;

	// test case body...

}

1	Replace the bean named `service` with a Mockito `mock`.

If no bean definition named service exists, one is created.

The following example shows how to use the default behavior of the @MockitoSpyBean annotation:

Java

class OverrideBeanTests {
	@MockitoSpyBean (1)
	private CustomService customService;

	// test case body...
}

1	Wrap the bean with type `CustomService` with a Mockito `spy`.

In the example above, we are wrapping the bean with type CustomService. If more than one bean of that type exists, the bean named customService is considered. Otherwise, the test will fail, and you will need to provide a qualifier of some sort to identify which of the CustomService beans you want to spy.

The following example uses a by-name lookup, rather than a by-type lookup:

Java

class OverrideBeanTests {
	@MockitoSpyBean(name = "service") (1)
	private CustomService customService;

	// test case body...

}

1	Wrap the bean named `service` with a Mockito `spy`.

@MockitoBean and @MockitoSpyBean

`@MockitoBean` and `@MockitoSpyBean`