Mocking void methods in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to mock a void method using Mockito.

JUnit

doNothing().when(mockedObject).[1]();

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AvoidMethod()

BvoidMethod(void)

CvoidMethod

DvoidMethod{}

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting parentheses after the method name inside when(), causing syntax errors.

The correct way to specify the method call in Mockito's doNothing().when() is with parentheses to indicate the method invocation. So, voidMethod() is correct.

2fill in blank

medium

Complete the code to verify that a void method was called exactly once.

JUnit

verify(mockedObject, [1]()).voidMethod();

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Atimes(0)

BatLeastOnce()

Cnever()

Dtimes(1)

Attempts:

3 left

💡 Hint

Common Mistakes

Using times(0) or never() when expecting the method to be called once.

To check that a method was called exactly once, use times(1) with verify().

3fill in blank

hard

Fix the error in the code to stub a void method to throw an exception.

JUnit

doThrow(new RuntimeException()).when(mockedObject).[1]();

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AvoidMethod{}

BvoidMethod[]

CvoidMethod()

DvoidMethod

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting parentheses after the method name inside when(), causing syntax errors.

When stubbing void methods with doThrow(), the method call should include parentheses inside when().

4fill in blank

hard

Fill both blanks to stub a void method to do nothing and verify it was called twice.

JUnit

do[1]().when(mockedObject).voidMethod();
verify(mockedObject, [2]()).voidMethod();

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ANothing

Btimes(1)

Ctimes(2)

DThrow(new RuntimeException())

Attempts:

3 left

💡 Hint

Common Mistakes

Using times(1) when expecting two calls.

Using doThrow() instead of doNothing() when no exception is expected.

doNothing() stubs the void method to do nothing, and times(2) verifies it was called twice.

5fill in blank

hard

Fill all three blanks to stub a void method to throw an exception, verify it was called once, and reset the mock.

JUnit

do[1](new RuntimeException()).when(mockedObject).voidMethod();
verify(mockedObject, [2]()).voidMethod();
[3](mockedObject);

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ANothing

Btimes(1)

Creset

DThrow

Attempts:

3 left

💡 Hint

Common Mistakes

Using doNothing() instead of doThrow() when expecting an exception.

Forgetting to reset the mock after verification.

doThrow() stubs the void method to throw an exception, times(1) verifies it was called once, and reset() clears the mock's interactions.