Mockito

Practice 20 Mockito interview questions with detailed answers. Part of the Testing track on Java Interview Hub.

• What is Mockito, and why is it used in unit testing?
• How do you mock an object in Mockito?
• What is the purpose of the @Mock and @InjectMocks annotations?
• How do you use when and thenReturn in Mockito?
• What is the difference between mock() and spy() in Mockito?
• How do you mock a method that returns void in Mockito?
• What are the use cases for doReturn(), doThrow(), and doAnswer() in Mockito?
• How do you verify the behavior of a mock object in Mockito?
• How do you mock an exception using Mockito?
• How does ArgumentCaptor work in Mockito? Can you give an example?
• How do you mock static methods in Mockito?
• What is the difference between verify() and verifyNoMoreInteractions() in Mockito?
• How do you mock final classes and methods in Mockito? Is it possible in earlier versions of Mockito?
• How would you mock dependencies that are passed to a method as parameters?
• How do you handle method chaining (e.g., foo.bar().baz()) in Mockito?
• What is the difference between a stub and a mock?
• How do you mock objects in Mockito when using constructor injection?
• Can you explain Mockito's RETURNS_DEEP_STUBS and its use case?
• How do you mock behavior for methods that depend on randomness (like Math.random())?
• How do you combine JUnit and Mockito to write comprehensive unit tests?