BeforeEachCallback and AfterEachCallback in JUnit - Test Execution Trace

Test Overview

This test demonstrates how BeforeEachCallback and AfterEachCallback work in JUnit 5. It verifies that setup code runs before each test and cleanup code runs after each test.

Test Code - JUnit 5

JUnit

import org.junit.jupiter.api.extension.BeforeEachCallback;
import org.junit.jupiter.api.extension.AfterEachCallback;
import org.junit.jupiter.api.extension.ExtensionContext;
import org.junit.jupiter.api.extension.RegisterExtension;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertTrue;

public class LifecycleExtensionTest {

    static class MyExtension implements BeforeEachCallback, AfterEachCallback {
        boolean beforeCalled = false;
        boolean afterCalled = false;

        @Override
        public void beforeEach(ExtensionContext context) {
            beforeCalled = true;
            System.out.println("BeforeEachCallback executed");
        }

        @Override
        public void afterEach(ExtensionContext context) {
            afterCalled = true;
            System.out.println("AfterEachCallback executed");
        }
    }

    @RegisterExtension
    static MyExtension extension = new MyExtension();

    @Test
    void testOne() {
        assertTrue(extension.beforeCalled, "BeforeEachCallback should have run before testOne");
        extension.beforeCalled = false; // reset for next test
    }

    @Test
    void testTwo() {
        assertTrue(extension.beforeCalled, "BeforeEachCallback should have run before testTwo");
        extension.beforeCalled = false; // reset for next test
    }

}

Execution Trace - 10 Steps

Step	Action	System State	Assertion	Result
1	JUnit starts testOne	Test lifecycle begins for testOne	-	PASS
2	MyExtension.beforeEach() runs	beforeCalled flag set to true	-	PASS
3	testOne executes assertion on beforeCalled	beforeCalled is true	assertTrue(extension.beforeCalled)	PASS
4	testOne resets beforeCalled to false	beforeCalled reset	-	PASS
5	MyExtension.afterEach() runs after testOne	afterCalled flag set to true	-	PASS
6	JUnit starts testTwo	Test lifecycle begins for testTwo	-	PASS
7	MyExtension.beforeEach() runs	beforeCalled flag set to true	-	PASS
8	testTwo executes assertion on beforeCalled	beforeCalled is true	assertTrue(extension.beforeCalled)	PASS
9	testTwo resets beforeCalled to false	beforeCalled reset	-	PASS
10	MyExtension.afterEach() runs after testTwo	afterCalled flag set to true	-	PASS

Failure Scenario

Failing Condition: MyExtension.beforeEach() does not set beforeCalled to true before test runs

Execution Trace Quiz - 3 Questions

What does BeforeEachCallback do in this test?

A Runs only once before all tests

B Runs setup code before each test method

C Runs cleanup code after all tests

D Skips the test if condition fails

Key Result

Using BeforeEachCallback and AfterEachCallback helps run setup and cleanup code automatically around each test, improving test reliability and reducing repeated code.