Argument captors in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an argument captor for a String argument.

JUnit

ArgumentCaptor<String> captor = ArgumentCaptor.[1];

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AforClass(String.class)

Bcapture()

CnewInstance()

Dof(String.class)

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'capture()' instead of 'forClass()' to create the captor.

Trying to instantiate ArgumentCaptor directly with 'new'.

The method forClass(String.class) creates an ArgumentCaptor for the String class.

2fill in blank

medium

Complete the code to verify a method call and capture its argument.

JUnit

verify(mockObject).someMethod([1]);

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Acaptor.capture()

Beq("test")

CanyString()

DisNull()

Attempts:

3 left

💡 Hint

Common Mistakes

Using matchers like 'anyString()' which do not capture the argument.

Passing a fixed value like 'eq("test")' instead of capturing.

Using captor.capture() tells Mockito to capture the argument passed to someMethod.

3fill in blank

hard

Fix the error in retrieving the captured value from the captor.

JUnit

String capturedValue = captor.[1]();

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Aget

BgetAllValues

CgetValue

Dcapture

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'getAllValues' which returns a list, not a single value.

Using 'capture' which is for capturing, not retrieving.

The method getValue() returns the single captured argument.

4fill in blank

hard

Fill both blanks to capture an argument and assert its value.

JUnit

verify(mock).process([1]);
assertEquals("expected", captor.[2]());

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Acapture()

BgetValue()

Ccapture

DgetValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'capture' without parentheses in the first blank.

Using 'getValue' without parentheses in the second blank.

Use capture() to capture the argument during verification and getValue() to retrieve it for assertion.

5fill in blank

hard

Fill all three blanks to capture multiple arguments and assert their values.

JUnit

verify(mock, times(2)).update([1]);
List<String> values = captor.[2]();
assertEquals("first", values.get([3]));

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Acapture()

BgetAllValues

C0

DgetValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'getValue' instead of 'getAllValues' to retrieve multiple arguments.

Using '1' instead of '0' as the index for the first element.

Use capture() to capture each argument, getAllValues() to get the list of captured arguments, and index 0 to check the first captured value.