Test classes and naming in JUnit - Test Execution Trace

Test Overview

This test class checks if the Calculator's add method correctly adds two numbers. It verifies that the sum is as expected.

Test Code - JUnit 5

JUnit

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

public class CalculatorTest {

    @Test
    public void testAdd() {
        Calculator calc = new Calculator();
        int result = calc.add(2, 3);
        assertEquals(5, result, "2 + 3 should equal 5");
    }
}

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

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test runner starts and loads CalculatorTest class	JUnit test environment initialized with CalculatorTest loaded	-	PASS
2	JUnit invokes testAdd method	Inside testAdd method, Calculator instance created	-	PASS
3	Calls Calculator.add(2, 3)	Calculator.add method executes and returns 5	-	PASS
4	Assert that result equals 5	Result is 5, expected is 5	assertEquals(5, result, "2 + 3 should equal 5")	PASS
5	Test method completes successfully	Test runner marks testAdd as passed	-	PASS

Failure Scenario

Failing Condition: Calculator.add method returns incorrect sum

Execution Trace Quiz - 3 Questions

What does the testAdd method verify?

A That Calculator multiplies two numbers

B That Calculator.add correctly adds two numbers

C That Calculator subtracts two numbers

D That Calculator divides two numbers

Key Result

Naming test classes with the suffix 'Test' clearly indicates their purpose and helps test runners identify them automatically.