@MockBean for mocking dependencies in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the @MockBean annotation in Spring Boot tests?

@MockBean creates a mock of a Spring bean and adds it to the application context during tests. It replaces the real bean with a mock to isolate the unit under test.

intermediate

How does @MockBean differ from using Mockito's @Mock annotation?

@MockBean integrates the mock into the Spring application context, replacing the real bean. @Mock only creates a mock object but does not replace any Spring beans.

intermediate

Can @MockBean be used to mock multiple beans of the same type in a Spring Boot test?

Yes, you can use multiple @MockBean annotations to mock different beans, but if there are multiple beans of the same type, you may need to specify the bean name to avoid conflicts.

beginner

Where should @MockBean be placed in a Spring Boot test class?

@MockBean is placed on fields inside the test class. Spring Boot will create and inject the mock bean into the application context before tests run.

advanced

What happens if you use @MockBean on a bean that is not present in the application context?

Spring Boot will add the mock bean to the context even if the original bean does not exist. This can be useful to add mocks for optional dependencies.

What does @MockBean do in a Spring Boot test?

A Replaces a Spring bean with a mock in the application context

B Creates a mock object but does not add it to the context

C Runs the real bean without mocking

D Deletes the bean from the application context

@MockBean replaces the real Spring bean with a mock version in the test context.

Where do you place the @MockBean annotation in your test code?

A On the test class itself

B On the main application class

C On fields inside the test class

D On the method under test

@MockBean is placed on fields inside the test class to inject mocks.

Which of these is a key difference between @MockBean and Mockito's @Mock?

A Both do the same thing

B <code>@Mock</code> replaces Spring beans, <code>@MockBean</code> does not

C <code>@MockBean</code> is only for integration tests

D <code>@MockBean</code> integrates with Spring context, <code>@Mock</code> does not

@MockBean adds mocks to Spring context; @Mock only creates mock objects.

If multiple beans of the same type exist, how can you specify which one to mock with @MockBean?

A Use the <code>name</code> attribute in <code>@MockBean</code>

B You cannot mock beans of the same type

C Mock all beans automatically

D Use <code>@Mock</code> instead

You can specify the bean name in @MockBean(name = "beanName") to target a specific bean.

What happens if @MockBean is used on a bean not defined in the Spring context?

A Test fails to start

B Mock bean is added to the context anyway

C Spring ignores the annotation

D The real bean is created instead

@MockBean adds the mock bean even if the original bean is missing.

Explain how @MockBean helps isolate components during Spring Boot testing.

Think about how you can test one part without running the whole app.

Describe the difference between @MockBean and Mockito's @Mock in Spring Boot tests.

Consider how Spring manages beans and how mocks fit in.