@ExtendWith annotation in JUnit - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the @ExtendWith annotation in JUnit?

The @ExtendWith annotation is used to register extensions in JUnit 5. Extensions add extra behavior to tests, like lifecycle callbacks or parameter injection.

intermediate

How do you apply multiple extensions using @ExtendWith?

You can apply multiple extensions by listing them inside @ExtendWith like this: @ExtendWith({Extension1.class, Extension2.class}).

beginner

True or False: @ExtendWith can only be used on test classes, not on individual test methods.

False. @ExtendWith can be used on both test classes and individual test methods to apply extensions at different scopes.

intermediate

What is a common use case for @ExtendWith in JUnit testing?

A common use case is to integrate third-party extensions like Mockito for mocking or to add custom behavior such as timing tests or managing resources.

advanced

Explain how @ExtendWith relates to JUnit 4's @RunWith annotation.

@ExtendWith in JUnit 5 replaces @RunWith from JUnit 4. It provides a more flexible way to add extensions compared to the older runner mechanism.

What does the @ExtendWith annotation do in JUnit 5?

A Marks a method as a test case

B Registers extensions to add behavior to tests

C Defines the order of test execution

D Skips a test method

@ExtendWith is used to register extensions that add extra behavior to tests, such as lifecycle callbacks or parameter injection.

How can you apply multiple extensions using @ExtendWith?

A By listing them in an array inside <code>@ExtendWith</code>

B By using multiple <code>@ExtendWith</code> annotations on the same class

C By calling extensions inside the test method

D By using <code>@RunWith</code> instead

You list multiple extensions inside curly braces like @ExtendWith({Ext1.class, Ext2.class}).

Can @ExtendWith be used on individual test methods?

A Only on interfaces

B No, only on classes

C Yes, it can be used on both classes and methods

D Only on constructors

@ExtendWith can be applied at class or method level to control extension scope.

Which JUnit 4 annotation is replaced by @ExtendWith in JUnit 5?

A <code>@RunWith</code>

B <code>@Test</code>

C <code>@Before</code>

D <code>@Ignore</code>

@ExtendWith replaces @RunWith to provide a more flexible extension mechanism.

Which of the following is NOT a typical use of @ExtendWith?

A Integrating third-party libraries like Mockito

B Adding custom test lifecycle behavior

C Injecting parameters into test methods

D Changing the test method's return type

@ExtendWith does not change method return types; it adds behavior or integrations.

Describe what the @ExtendWith annotation does and give an example of when you might use it.

Think about how you can add extra features to tests without changing test code.

Explain how @ExtendWith differs from JUnit 4's @RunWith annotation.

Consider flexibility and scope of application.