What\'s the Difference Between `@Mock` and `@InjectMocks` in Mockito?

Delineating @Mock and @InjectMocks in Mockito Framework

The Mockito framework provides annotations that aid in mocking objects during testing. Two commonly used annotations are @Mock and @InjectMocks, which play distinct roles in the mocking process.

@Mock: A Mock Creation Annotation

Simply put, @Mock serves to create a mock object. It generates a dummy object that implements a specific interface or extends a specific class. Mock objects are used to replace real dependencies during testing, allowing for the isolation of individual components and the simulation of specific scenarios.

@InjectMocks: Injecting Mocks into a Class Instance

In contrast to @Mock, @InjectMocks is a more advanced annotation that combines mocking and dependency injection. It creates an instance of the class under test and, importantly, injects the mock objects created with @Mock (or @Spy) annotations into this instance.

For @InjectMocks to function correctly, it is essential to use @RunWith(MockitoJUnitRunner.class) or Mockito.initMocks(this) to initialize and inject the mock dependencies into the class instance. With JUnit 5, the @ExtendWith(MockitoExtension.class) annotation is required.

Here's an example that leverages both annotations:

// JUnit 4
@RunWith(MockitoJUnitRunner.class)
public class SomeManagerTest {
   // ...

    @InjectMocks
    private SomeManager someManager;

    @Mock
    private SomeDependency someDependency; // This mock will be injected into someManager
   
    // ... // Tests ...

}

By using @InjectMocks, the SomeManager instance will be created with the mock object for SomeDependency injected, allowing the test cases to focus on testing the behavior of SomeManager while interacting with its mock dependency. This facilitates the isolation and testing of specific scenarios without relying on real dependencies.

The above is the detailed content of What\'s the Difference Between `@Mock` and `@InjectMocks` in Mockito?. For more information, please follow other related articles on the PHP Chinese website!