Verify package-level test organization with JUnit

Preconditions (2)

Step 1: Run all tests in the package 'com.example.utils'

Step 2: Verify that all test classes in 'com.example.utils' package are executed

Step 3: Run all tests in the package 'com.example.services'

Step 4: Verify that all test classes in 'com.example.services' package are executed

✅ Expected Result: All tests in the specified packages run successfully and report correct pass/fail status

Automation Requirements - JUnit 5

Assertions Needed:

Verify test execution count matches number of test classes in package

Verify all tests pass in the package

Best Practices:

Use JUnit Platform Launcher API to run tests by package

Use assertions to verify test results

Organize tests in packages matching source code structure

Automated Solution

JUnit

import org.junit.platform.engine.DiscoverySelector;
import org.junit.platform.engine.discovery.DiscoverySelectors;
import org.junit.platform.launcher.Launcher;
import org.junit.platform.launcher.LauncherDiscoveryRequest;
import org.junit.platform.launcher.LauncherDiscoveryRequestBuilder;
import org.junit.platform.launcher.LauncherFactory;
import org.junit.platform.launcher.listeners.SummaryGeneratingListener;
import org.junit.platform.launcher.listeners.TestExecutionSummary;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

public class PackageLevelTestRunner {

    public static void main(String[] args) {
        runTestsInPackage("com.example.utils");
        runTestsInPackage("com.example.services");
    }

    private static void runTestsInPackage(String packageName) {
        LauncherDiscoveryRequest request = LauncherDiscoveryRequestBuilder.request()
                .selectors(DiscoverySelectors.selectPackage(packageName))
                .build();

        Launcher launcher = LauncherFactory.create();
        SummaryGeneratingListener listener = new SummaryGeneratingListener();

        launcher.registerTestExecutionListeners(listener);
        launcher.execute(request);

        TestExecutionSummary summary = listener.getSummary();

        System.out.println("Package: " + packageName);
        System.out.println("Tests found: " + summary.getTestsFoundCount());
        System.out.println("Tests succeeded: " + summary.getTestsSucceededCount());
        System.out.println("Tests failed: " + summary.getTestsFailedCount());

        // Assertions to verify all tests passed
        assertTrue(summary.getTestsFoundCount() > 0, "No tests found in package " + packageName);
        assertEquals(0, summary.getTestsFailedCount(), "Some tests failed in package " + packageName);
    }
}

This code uses JUnit 5's Launcher API to run all tests in a given package.

The runTestsInPackage method builds a discovery request selecting the package, then executes it with a launcher.

A SummaryGeneratingListener collects test results.

After execution, it prints the number of tests found, succeeded, and failed.

Assertions check that at least one test was found and that no tests failed.

This approach ensures package-level test organization is verified by running all tests in the package and checking their results.

Common Mistakes - 3 Pitfalls

Using hardcoded test class selectors instead of package selectors

Not checking if any tests were found before asserting success

Ignoring test failures and not asserting on them

Bonus Challenge

Now add data-driven testing with 3 different package names to run tests dynamically

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