Why assertions verify expected outcomes in JUnit - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assert that the sum of 2 and 3 equals 5.

JUnit

assertEquals([1], 2 + 3);

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A5

B7

C4

D6

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong expected value like 6 or 4.

Confusing actual and expected values.

The assertion checks if 2 + 3 equals 5, which is the expected outcome.

2fill in blank

medium

Complete the code to assert that the string "hello" starts with "he".

JUnit

assertTrue("hello".[1]("he"));

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AendsWith

BstartsWith

Ccontains

Dequals

Attempts:

3 left

💡 Hint

Common Mistakes

Using endsWith instead of startsWith.

Using equals which checks full string equality.

The assertion verifies that the string "hello" starts with the substring "he".

3fill in blank

hard

Fix the error in the assertion that checks if a list is empty.

JUnit

assertTrue([1].isEmpty());

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AmyList.get(0)

BmyList.size()

CmyList

DmyList.isEmpty

Attempts:

3 left

💡 Hint

Common Mistakes

Calling isEmpty on size() or get(0) which are not boolean methods.

Using isEmpty without parentheses.

The method isEmpty() is called on the list object myList to check if it is empty.

4fill in blank

hard

Fill both blanks to assert that the multiplication of 4 and 5 equals 20.

JUnit

assertEquals([1], [2] * 5);

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A4

B20

C6

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using 20 as the first blank and 20 as the second blank causing wrong multiplication.

Using 6 or 3 which do not produce 20 when multiplied by 5.

The assertion checks if 4 * 5 equals 20 by using 4 as the variable and multiplying by 5.

5fill in blank

hard

Fill all three blanks to assert that the substring "test" is contained in "unittesting".

JUnit

assertTrue("unittesting".[1]([2].[3]()));

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Acontains

B"test"

CtoString

DstartsWith

Attempts:

3 left

💡 Hint

Common Mistakes

Using startsWith instead of contains.

Not converting the substring to string before checking.

The assertion checks if the string "unittesting" contains the substring "test" converted to string.