verify() for interaction verification in JUnit - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of verify() in interaction verification?

verify() checks if a specific method was called on a mock object during the test. It helps confirm that the expected interactions happened.

beginner

How do you use verify() to check a method was called exactly once?

Use verify(mockObject).methodName(args); to check the method was called once.

beginner

What happens if verify() fails during a test?

The test fails with an error showing that the expected method call did not happen as specified.

intermediate

How can you verify a method was never called?

Use verify(mockObject, never()).methodName(args); to check the method was not called at all.

intermediate

Explain the difference between verify() and verifyNoMoreInteractions().

verify() checks specific method calls, while verifyNoMoreInteractions() ensures no other calls happened on the mock beyond those verified.

What does verify(mock).someMethod() check in a test?

A That <code>someMethod()</code> was never called

B That <code>mock</code> is not null

C That <code>someMethod()</code> returned true

D That <code>someMethod()</code> was called on <code>mock</code> exactly once

verify() confirms the method was called once on the mock.

How do you verify a method was called exactly twice?

A verify(mock).method();

B verify(mock, once()).method();

C verify(mock, times(2)).method();

D verify(mock, never()).method();

Use times(2) with verify() to check two calls.

What is the result if verify() does not find the expected method call?

A Test passes silently

B Test fails with an error

C Test skips the verification

D Test logs a warning but passes

Missing expected calls cause test failure.

Which method verifies no other interactions happened on a mock?

A verifyNoMoreInteractions(mock);

B verify(mock);

C verify(mock, never());

D verifyZeroInteractions(mock);

verifyNoMoreInteractions() ensures no unexpected calls.

To check a method was never called, which syntax is correct?

A verify(mock, never()).method();

B verify(mock).method();

C verify(mock, times(0)).method();

D verifyNoMoreInteractions(mock);

never() explicitly checks zero calls.

Describe how verify() helps in testing interactions with mock objects.

Think about confirming what your code did with the mock.

Explain the difference between verifying a method call and verifying no more interactions.

One is about specific calls, the other about unexpected calls.