Why fast tests enable frequent runs in JUnit - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to mark the test method with JUnit 5 annotation.

JUnit

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

public class CalculatorTest {
    [1]
    void testAddition() {
        int sum = 2 + 3;
        assertEquals(5, sum);
    }
}

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

A@AfterAll

B@BeforeEach

C@Test

D@Disabled

Attempts:

3 left

💡 Hint

Common Mistakes

Using @BeforeEach instead of @Test

Forgetting to add any annotation

Using @Disabled which skips the test

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

2fill in blank

medium

Complete the code to assert that the result equals 10.

JUnit

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

@Test
void testMultiplication() {
    int result = 2 * 5;
    [1](10, result);
}

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

AassertEquals

BassertTrue

CassertNull

DassertFalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using assertTrue with equality expression instead of assertEquals

Using assertNull which checks for null values

assertEquals(expected, actual) checks if the actual value matches the expected value.

3fill in blank

hard

Fix the error in the test method to make it run correctly.

JUnit

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

@Test
void testDivision() {
    int result = 10 / 2;
    assertEquals(5, [1]);
}

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

Aresult

B10

C2

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using a literal number instead of the variable 'result'

Swapping expected and actual arguments

The actual value to check is the variable 'result', not a literal.

4fill in blank

hard

Fill both blanks to create a fast test that runs multiple times.

JUnit

import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.RepeatedTest;

@RepeatedTest([1])
void testFastAddition() {
    int sum = 1 + 1;
    assertEquals([2], sum);
}

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

A5

B2

C3

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong number of repetitions

Asserting wrong expected sum

RepeatedTest(10) runs the test 10 times; sum of 1 + 1 equals 2.

5fill in blank

hard

Fill all three blanks to create a test that fails fast on wrong input.

JUnit

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

@Test
void testFailFast() {
    int input = [1];
    int expected = [2];
    int actual = input * 2;
    assertEquals([3], actual);
}

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

A3

B4

C6

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatching expected and actual values

Using input that does not match expected output

Input 3 doubled is 6, so expected and actual should be 6 to pass the test.