Mocking static methods (Mockito 3.4+) in JUnit - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is mocking static methods in Mockito 3.4+?

Mocking static methods means creating fake versions of static methods to control their behavior during tests, allowing you to test code that depends on static methods without running the real ones.

beginner

How do you start mocking static methods in Mockito 3.4+?

You use the try-with-resources block with Mockito.mockStatic(ClassName.class) to create a mock scope for static methods, ensuring the mock is closed after use.

intermediate

Why should you use try-with-resources when mocking static methods?

Because it automatically closes the static mock after the test, preventing side effects on other tests and keeping tests isolated.

beginner

What is the syntax to mock a static method call to return a specific value?

Inside the mockStatic block, use mockStatic.when(() -> ClassName.staticMethod(args)).thenReturn(value) to specify the fake return value.

intermediate

Can you verify static method calls with Mockito 3.4+? How?

Yes, inside the mockStatic block, use mockStatic.verify(() -> ClassName.staticMethod(args)) to check if the static method was called as expected.

Which Mockito feature allows mocking static methods starting from version 3.4+?

A Mockito.spy()

B Mockito.mock()

C Mockito.when()

D Mockito.mockStatic()

Mockito.mockStatic() is the method introduced in Mockito 3.4+ to mock static methods.

Why is try-with-resources recommended when mocking static methods?

A To automatically close the static mock and avoid side effects

B To improve test speed

C To mock instance methods

D To create multiple mocks

Try-with-resources ensures the static mock is closed after use, preventing interference with other tests.

How do you specify a return value for a mocked static method?

A doReturn(value).when(ClassName).staticMethod(args)

B when(ClassName.staticMethod(args)).thenReturn(value)

C verify(ClassName).staticMethod(args)

D mockStatic(ClassName).thenReturn(value)

Inside the mockStatic block, use when(...).thenReturn(...) to define the return value.

Can you verify static method calls in Mockito 3.4+?

A Only with Mockito 2.x

B No, static methods cannot be verified

C Yes, using verify() inside the mockStatic block

D Yes, but only outside the mockStatic block

Mockito 3.4+ allows verification of static method calls inside the mockStatic block.

What happens if you don't close the static mock after testing?

A Other tests might be affected by the mock

B The test will fail immediately

C The static method will not be mocked

D Mockito will throw an exception

Not closing the static mock can cause side effects on other tests, breaking test isolation.

Explain how to mock a static method using Mockito 3.4+ and why it is important to use try-with-resources.

Think about resource management and test isolation.

Describe how to verify that a static method was called during a test using Mockito 3.4+.

Verification is similar to instance method verification but inside the static mock scope.