Coverage reports in JUnit - Test Execution Trace

Test Overview

This test runs a simple JUnit test case and generates a coverage report to verify which parts of the code were executed during the test.

Test Code - JUnit 5

JUnit

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

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

    public int subtract(int a, int b) {
        return a - b;
    }
}

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

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test runner starts and loads CalculatorTest class	JUnit test environment initialized	-	PASS
2	JUnit executes testAdd() method	Calculator instance created, add method called with (2,3)	assertEquals(5, calc.add(2, 3)) verifies result is 5	PASS
3	Test completes successfully	Test method finished without exceptions	-	PASS
4	Coverage tool analyzes which methods were executed	Coverage data collected for add() method, subtract() method not executed	Coverage report shows add() method covered, subtract() method not covered	PASS
5	Coverage report generated and saved	Report file available with coverage summary	Report confirms 50% method coverage for Calculator class	PASS

Failure Scenario

Failing Condition: TestAdd method fails assertion or coverage tool fails to generate report

Execution Trace Quiz - 3 Questions

What does the coverage report indicate after running the testAdd() method?

A No methods were covered

B Only the add() method was executed and covered

C Both add() and subtract() methods were covered

D Only subtract() method was covered

Key Result

Generating coverage reports helps identify which parts of the code are tested and which are not, guiding better test coverage and quality.