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

Recall & Review

beginner

What is the purpose of the @MockBean annotation in Spring testing?

@MockBean creates and injects a mock of a Spring bean into 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 Mockito's @Mock annotation?

@MockBean integrates with Spring's application context and replaces beans there, while @Mock creates a mock object but does not replace Spring beans automatically.

beginner

Where should you place the @MockBean annotation in a Spring Boot test?

<p>You place <code>@MockBean</code> on a field in your test class where you want Spring to inject the mock bean instead of the real one.</p>

beginner

Can @MockBean be used to mock multiple beans in the same test?

<p>Yes, you can declare multiple <code>@MockBean</code> fields in the same test class to mock different beans as needed.</p>

intermediate

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

Spring will add the mock bean to the context, so it can be used by other beans or the test, even if the original bean was not defined.

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 affect Spring beans

C Runs the real bean without mocking

D Disables Spring context loading

@MockBean replaces the real Spring bean with a mock in the application context during tests.

Where do you declare @MockBean in your test code?

A Inside the bean class

B On the main application class

C On a field in the test class

D In the application.properties file

You declare @MockBean on a field in the test class to inject the mock bean.

Which of these is a key benefit of using @MockBean over @Mock?

A It disables all beans except mocks

B It runs tests faster by skipping mocks

C It automatically generates test data

D It integrates mocks into Spring's application context

@MockBean integrates mocks into Spring's context, replacing real beans.

Can you use multiple @MockBean annotations in one test class?

A Only in integration tests

B Yes, to mock multiple beans

C Only if beans are of the same type

D No, only one mock bean per test

You can declare multiple @MockBean fields to mock different beans.

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

A Spring adds the mock bean to the context

B Test fails to start

C Mock is ignored

D Spring throws an error

Spring adds the mock bean to the context even if the original bean was missing.

Explain how @MockBean helps isolate units in Spring Boot tests.

Think about how mocking helps focus on one part of the code.

Describe the difference between @MockBean and @Mock in Spring testing.

Consider how Spring manages beans versus plain mocks.