when().thenReturn() stubbing in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to stub the method call using Mockito.

JUnit

when(mockedList.[1]()).thenReturn("hello");

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Aget(0)

Badd("test")

Cclear()

Dsize()

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to stub void methods like clear() or add() which do not return values.

Using size() which returns an int, not a String.

The get(0) method is stubbed to return "hello" when called on the mocked list.

2fill in blank

medium

Complete the code to stub the size() method to return 5.

JUnit

when(mockedList.[1]()).thenReturn(5);

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Asize()

Blength()

Csize

Dget(0)

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting parentheses in method call.

Using incorrect method names like size or length().

The size() method is stubbed correctly with parentheses to return 5.

3fill in blank

hard

Fix the error in the stubbing code below.

JUnit

when(mockedList.get([1])).thenReturn("world");

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Anull

B"0"

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a string instead of an integer index.

Using null or negative index values.

The index argument must be an integer, so 0 is correct. Using a string or null causes errors.

4fill in blank

hard

Fill both blanks to stub mockedMap.get() to return 10 when key "score" is used.

JUnit

when(mockedMap.[1]([2])).thenReturn(10);

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Aget

B"score"

Cput

Dremove

Attempts:

3 left

💡 Hint

Common Mistakes

Using put or remove which are void or different methods.

Not passing the key as a string.

The get method is stubbed with the key "score" to return 10.

5fill in blank

hard

Fill all three blanks to stub mockedService.calculate() to return 42 when called with 5.

JUnit

when(mockedService.[1]([2])).thenReturn([3]);

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Acalculate

B5

C42

Dcompute

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong method names like compute.

Passing arguments or return values as strings instead of numbers.

The calculate method is stubbed with argument 5 to return 42.