Verification times (times, never, atLeast) in JUnit - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does verify(mock, times(n)) do in JUnit testing?

It checks that the mock method was called exactly n times during the test execution.

beginner

Explain the use of verify(mock, never()).

It verifies that the mock method was never called during the test. This ensures no interaction happened with that method.

intermediate

What does verify(mock, atLeast(n)) check?

It checks that the mock method was called at least n times, meaning n or more times.

beginner

Why is verification important in unit testing with mocks?

Verification confirms that the code interacts with dependencies as expected, ensuring correct behavior and catching unexpected calls.

beginner

How would you verify a method was called exactly once using JUnit and Mockito?

Use verify(mock, times(1)).methodName() to check the method was called exactly one time.

What does verify(mock, never()).someMethod() ensure?

A The method was called at least once

B The method was called exactly once

C The method was never called

D The method was called multiple times

Using never() verifies that the method was not called at all.

Which verification checks if a method was called at least 3 times?

A verify(mock, times(3))

B verify(mock, never())

C verify(mock, atMost(3))

D verify(mock, atLeast(3))

atLeast(3) verifies the method was called 3 or more times.

What happens if verify(mock, times(2)) is used but the method was called only once?

A Test passes

B Test fails with verification error

C Test ignores verification

D Test retries the method call

The test fails because the method was not called the expected number of times.

Which verification is used to confirm no interaction with a mock method?

A never()

B times(0)

C atLeast(1)

D times(1)

never() explicitly checks that the method was never called.

If you want to verify a method was called exactly once, which is the best choice?

A verify(mock, times(1))

B verify(mock, atLeast(1))

C verify(mock, never())

D verify(mock, atMost(1))

times(1) ensures the method was called exactly one time.

Describe how you would verify method call counts using JUnit and Mockito.

Think about how to check if a method was called zero, exactly, or at least a number of times.

Explain why verifying method calls is important in unit tests with mocks.

Consider what happens if dependencies are called incorrectly or unexpectedly.