Coverage thresholds in JUnit - Test Execution Trace

Test Overview

This test runs unit tests and checks if the code coverage meets the minimum required thresholds for instructions, branches, and lines. It verifies that the coverage is above the set limits to ensure good test quality.

Test Code - JUnit 5

JUnit

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

public class CoverageThresholdTest {

    @Test
    void sampleTest() {
        int result = add(2, 3);
        assertEquals(5, result);
    }

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

    // Note: Coverage thresholds are usually configured in build tools like Maven or Gradle,
    // but here we simulate a check by asserting coverage values.

    @Test
    void coverageThresholdCheck() {
        // Simulated coverage values (in percent)
        int instructionCoverage = 85;
        int branchCoverage = 80;
        int lineCoverage = 90;

        int minInstructionCoverage = 80;
        int minBranchCoverage = 75;
        int minLineCoverage = 85;

        assertTrue(instructionCoverage >= minInstructionCoverage, "Instruction coverage below threshold");
        assertTrue(branchCoverage >= minBranchCoverage, "Branch coverage below threshold");
        assertTrue(lineCoverage >= minLineCoverage, "Line coverage below threshold");
    }
}

Execution Trace - 4 Steps

Step	Action	System State	Assertion	Result
1	Test runner starts and loads CoverageThresholdTest class	JUnit test environment initialized	-	PASS
2	Runs sampleTest method	Method add(2,3) returns 5	assertEquals(5, result)	PASS
3	Runs coverageThresholdCheck method	Simulated coverage values: instruction=85%, branch=80%, line=90%	assertTrue(instructionCoverage >= 80), assertTrue(branchCoverage >= 75), assertTrue(lineCoverage >= 85)	PASS
4	Test runner completes all tests	All tests passed	-	PASS

Failure Scenario

Failing Condition: One or more coverage values are below the minimum thresholds

Execution Trace Quiz - 3 Questions

What does the coverageThresholdCheck test verify?

A That the test runner starts correctly

B That the add method returns correct sums

C That code coverage percentages meet minimum required thresholds

D That the coverage tool is installed

Key Result

Setting coverage thresholds helps maintain good test quality by ensuring enough code is tested, preventing unnoticed bugs.