Why coverage measures test completeness in JUnit - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a JUnit test method that checks if a number is positive.

JUnit

import static org.junit.jupiter.api.Assertions.assertTrue;
import org.junit.jupiter.api.Test;

public class NumberTest {
    @Test
    public void testPositive() {
        int number = 5;
        assertTrue(number [1] 0);
    }
}

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

A==

B<

C>

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' causes the test to fail for positive numbers.

The assertion checks if the number is greater than zero, meaning it is positive.

2fill in blank

medium

Complete the code to assert that a string is not null in a JUnit test.

JUnit

import static org.junit.jupiter.api.Assertions.assertNotNull;
import org.junit.jupiter.api.Test;

public class StringTest {
    @Test
    public void testStringNotNull() {
        String text = "hello";
        assertNotNull([1]);
    }
}

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

Atext

Bnull

C"hello"

Dempty

Attempts:

3 left

💡 Hint

Common Mistakes

Passing 'null' or a string literal instead of the variable causes the test to fail.

The assertion checks that the variable 'text' is not null.

3fill in blank

hard

Fix the error in the JUnit test assertion that checks equality of two integers.

JUnit

import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;

public class EqualityTest {
    @Test
    public void testEqualNumbers() {
        int expected = 10;
        int actual = 5 + 5;
        assertEquals([1], actual);
    }
}

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

A10

Bactual

C5

Dexpected

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping expected and actual arguments causes confusing test results.

The first argument to assertEquals should be the expected value, which is 'expected'.

4fill in blank

hard

Fill both blanks to complete a JUnit test that checks if a list contains a specific element.

JUnit

import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.List;
import org.junit.jupiter.api.Test;

public class ListTest {
    @Test
    public void testListContains() {
        List<String> fruits = List.of("apple", "banana", "cherry");
        assertTrue(fruits.[1]("banana") [2] true);
    }
}

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

Acontains

Bequals

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'equals' instead of 'contains' or wrong comparison operators.

The method 'contains' checks if the list has the element. The '==' operator compares the result to true.

5fill in blank

hard

Fill all three blanks to complete a JUnit test that verifies a map contains a key and its value is correct.

JUnit

import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.Map;
import org.junit.jupiter.api.Test;

public class MapTest {
    @Test
    public void testMapKeyValue() {
        Map<String, Integer> ages = Map.of("Alice", 30, "Bob", 25);
        assertEquals([1], ages.get([2]));
        assertEquals([3], ages.size());
    }
}

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

A30

B"Alice"

C2

D"Bob"

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong keys or values, or incorrect map size in assertions.

The test checks that the value for key "Alice" is 30 and the map size is 2.