Why JUnit is the standard for Java testing - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a basic JUnit test method.

JUnit

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

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

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AIgnore

BBeforeEach

CAfterAll

DTest

Attempts:

3 left

💡 Hint

Common Mistakes

Using @BeforeEach instead of @Test for test methods.

Forgetting the @Test annotation entirely.

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

2fill in blank

medium

Complete the assertion to check if two strings are equal.

JUnit

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.[1];

public class StringTest {
    @Test
    void testEquality() {
        String expected = "hello";
        String actual = "hello";
        [1](expected, actual);
    }
}

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AassertNull

BassertTrue

CassertEquals

DassertSame

Attempts:

3 left

💡 Hint

Common Mistakes

Using assertTrue with a direct comparison instead of assertEquals.

Using assertSame which checks object identity, not equality.

assertEquals checks if two values are equal, which is perfect for comparing strings.

3fill in blank

hard

Fix the error in the test method to correctly expect an exception.

JUnit

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

public class ExceptionTest {
    @Test
    void testException() {
        assertThrows([1].class, () -> {
            Integer.parseInt("abc");
        });
    }
}

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ANumberFormatException

BIllegalArgumentException

CNullPointerException

DIOException

Attempts:

3 left

💡 Hint

Common Mistakes

Using NullPointerException which is unrelated here.

Using IOException which is for input/output errors.

The NumberFormatException is thrown when parsing a non-numeric string to an integer.

4fill in blank

hard

Fill in the blank to create a parameterized test that runs with multiple inputs.

JUnit

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
import static org.junit.jupiter.api.Assertions.assertTrue;

public class ParameterizedTestExample {
    @[1]
    @ValueSource(strings = {"racecar", "radar", "level"})
    void testPalindrome(String word) {
        assertTrue(word.equals(new StringBuilder(word).reverse().toString()));
    }
}

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ATest

BParameterizedTest

CBeforeAll

DAfterEach

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Test instead of @ParameterizedTest for parameterized tests.

Missing the @ParameterizedTest annotation.

The @ParameterizedTest annotation tells JUnit to run the test multiple times with different inputs.

5fill in blank

hard

Fill all three blanks to create a test suite that runs multiple test classes.

JUnit

import org.junit.platform.suite.api.SelectClasses;
import org.junit.platform.suite.api.Suite;

@Suite
@SelectClasses([1].class, [2].class)
public class [3] {
}

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ACalculatorTest

BStringTest

CAllTests

DExceptionTest

Attempts:

3 left

💡 Hint

Common Mistakes

Using test class names not imported or defined.

Naming the suite class incorrectly.

The @SelectClasses annotation lists test classes to run. The class name for the suite is AllTests.