@Nested inner classes in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a nested test class using JUnit 5.

JUnit

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;

public class CalculatorTest {

    @[1]
    class AdditionTests {

        @Test
        void testAddPositiveNumbers() {
            // test code here
        }
    }
}

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ATest

BNested

CBeforeEach

DDisplayName

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Test instead of @Nested for inner classes.

Forgetting to import the @Nested annotation.

The @Nested annotation is used to declare an inner test class in JUnit 5.

2fill in blank

medium

Complete the code to run a test method inside a nested class.

JUnit

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;

public class StringUtilsTest {

    @Nested
    class TrimTests {

        @[1]
        void testTrimSpaces() {
            // test code here
        }
    }
}

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ATest

BBeforeEach

CAfterEach

DDisabled

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Nested on methods instead of classes.

Forgetting to annotate test methods with @Test.

The @Test annotation marks a method as a test method in JUnit 5.

3fill in blank

hard

Fix the error in the nested test class declaration.

JUnit

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;

public class MathTest {

    @Nested
    static class [1] {

        @Test
        void testMultiply() {
            // test code here
        }
    }
}

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AMultiplicationTests

BMultiplyTests

CMultiplicationTest

DMultiplyTest

Attempts:

3 left

💡 Hint

Common Mistakes

Using static modifier on nested test classes (JUnit 5 requires non-static).

Using singular form for class name which is less clear.

Nested test classes must be non-static in JUnit 5, but the question asks to fix the error by naming the class properly. The class name should be a plural form to indicate multiple tests, so 'MultiplicationTests' is best practice.

4fill in blank

hard

Fill both blanks to correctly declare and annotate a nested test class and its test method.

JUnit

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;

public class ListTest {

    @[1]
    class RemoveTests {

        @[2]
        void testRemoveByIndex() {
            // test code here
        }
    }
}

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ANested

BTest

CBeforeEach

DAfterEach

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping @Test and @Nested annotations.

Forgetting to annotate either the class or the method.

The nested class must be annotated with @Nested and the test method with @Test to run properly.

5fill in blank

hard

Fill all three blanks to create a nested test class with a test method and a display name annotation.

JUnit

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.DisplayName;

public class CalculatorTest {

    @[1]
    @[2]("Addition operations")
    class AdditionTests {

        @[3]
        void testAddPositiveNumbers() {
            // test code here
        }
    }
}

Drag options to blanks, or click blank then click option'

ANested

BDisplayName

CTest

DBeforeEach

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting @DisplayName on the nested class.

Not annotating the test method with @Test.

The nested class is annotated with @Nested and @DisplayName to describe the group, and the test method is annotated with @Test.