JUnit 4 vs JUnit 5 (Jupiter) differences - Test Execution Compared

Test Overview

This test checks a simple calculator addition method using both JUnit 4 and JUnit 5 styles. It verifies that the addition result is correct and shows how assertions and annotations differ between the two versions.

Test Code - JUnit

JUnit

import static org.junit.Assert.assertEquals;
import org.junit.Test;

public class CalculatorTestJUnit4 {
    @Test
    public void testAdd() {
        Calculator calc = new Calculator();
        int result = calc.add(2, 3);
        assertEquals(5, result);
    }
}

// JUnit 5 version
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;

public class CalculatorTestJUnit5 {
    @Test
    void testAdd() {
        Calculator calc = new Calculator();
        int result = calc.add(2, 3);
        assertEquals(5, result);
    }
}

// Calculator class
public class Calculator {
    public int add(int a, int b) {
        return a + b;
    }
}

Execution Trace - 10 Steps

Step	Action	System State	Assertion	Result
1	JUnit 4 test runner starts and loads CalculatorTestJUnit4 class	JUnit 4 environment ready, test class loaded	-	PASS
2	JUnit 4 runner finds @Test method testAdd() and invokes it	CalculatorTestJUnit4 instance created	-	PASS
3	testAdd() calls Calculator.add(2, 3) which returns 5	Calculator instance created and method executed	-	PASS
4	JUnit 4 assertEquals(5, result) verifies the result is 5	Assertion compares expected and actual values	assertEquals passes if expected == actual	PASS
5	JUnit 4 test completes successfully	Test marked as passed	-	PASS
6	JUnit 5 test runner starts and loads CalculatorTestJUnit5 class	JUnit 5 environment ready, test class loaded	-	PASS
7	JUnit 5 runner finds @Test method testAdd() and invokes it	CalculatorTestJUnit5 instance created	-	PASS
8	testAdd() calls Calculator.add(2, 3) which returns 5	Calculator instance created and method executed	-	PASS
9	JUnit 5 assertEquals(5, result) verifies the result is 5	Assertion compares expected and actual values	assertEquals passes if expected == actual	PASS
10	JUnit 5 test completes successfully	Test marked as passed	-	PASS

Failure Scenario

Failing Condition: Calculator.add() returns wrong result, e.g., 4 instead of 5

Execution Trace Quiz - 3 Questions

Which annotation is used to mark test methods in both JUnit 4 and JUnit 5?

A @Test

B @Before

C @RunWith

D @TestMethod

Key Result

Using consistent annotations like @Test and clear assertion imports helps keep tests readable and maintainable across JUnit versions.