@Execution annotation in JUnit - Test Execution Trace

Test Overview

This test demonstrates how to use the @Execution annotation in JUnit 5 to control the execution mode of test methods within a test class. It verifies that tests run in the specified concurrent mode.

Test Code - JUnit 5

JUnit

import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.parallel.Execution;
import org.junit.jupiter.api.parallel.ExecutionMode;
import static org.junit.jupiter.api.Assertions.assertTrue;

@Execution(ExecutionMode.CONCURRENT)
public class ParallelExecutionTest {

    @Test
    void testOne() throws InterruptedException {
        Thread.sleep(100); // Simulate work
        assertTrue(true);
    }

    @Test
    void testTwo() throws InterruptedException {
        Thread.sleep(100); // Simulate work
        assertTrue(true);
    }
}

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	JUnit test runner starts the ParallelExecutionTest class	Test class loaded with @Execution(ExecutionMode.CONCURRENT) annotation	-	PASS
2	JUnit identifies testOne() method and schedules it for execution	testOne() ready to run concurrently	-	PASS
3	JUnit identifies testTwo() method and schedules it for execution concurrently with testOne()	testTwo() ready to run concurrently	-	PASS
4	testOne() executes: sleeps 100ms then asserts true	testOne() running	assertTrue(true) verifies condition is true	PASS
5	testTwo() executes concurrently: sleeps 100ms then asserts true	testTwo() running	assertTrue(true) verifies condition is true	PASS
6	JUnit completes both tests and reports results	Both tests finished successfully	Both assertions passed	PASS

Failure Scenario

Failing Condition: If the @Execution annotation is missing or set to ExecutionMode.SAME_THREAD, tests run sequentially, not concurrently as expected.

Execution Trace Quiz - 3 Questions

What does the @Execution(ExecutionMode.CONCURRENT) annotation do in this test?

A Runs test methods one after another sequentially

B Runs test methods in parallel threads

C Disables all tests in the class

D Runs tests only on the main thread

Key Result

Using @Execution(ExecutionMode.CONCURRENT) allows tests to run in parallel, improving test suite speed. Always verify the annotation is present to enable concurrency.