BeforeEachCallback and AfterEachCallback in JUnit - Build an Automation Script

Automate setup and cleanup using BeforeEachCallback and AfterEachCallback in JUnit

Preconditions (2)

Step 1: Create a class that implements BeforeEachCallback and AfterEachCallback interfaces

Step 2: In the beforeEach method, add code to print 'Setup before each test'

Step 3: In the afterEach method, add code to print 'Cleanup after each test'

Step 4: Register this callback class as an extension in the test class using @ExtendWith

Step 5: Write two simple test methods that assert basic conditions

Step 6: Run the tests and observe the console output for setup and cleanup messages before and after each test

✅ Expected Result: Each test method runs successfully, and console output shows 'Setup before each test' before each test and 'Cleanup after each test' after each test

Automation Requirements - JUnit 5

Assertions Needed:

Verify that test methods pass

Verify that BeforeEachCallback and AfterEachCallback methods are invoked for each test

Best Practices:

Use @ExtendWith to register extensions

Keep setup and cleanup code separate from test logic

Use descriptive method names

Avoid side effects in callbacks

Automated Solution

JUnit

import org.junit.jupiter.api.Test;
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.ExtendWith;
import static org.junit.jupiter.api.Assertions.assertTrue;

class SetupCleanupExtension implements BeforeEachCallback, AfterEachCallback {
    @Override
    public void beforeEach(ExtensionContext context) {
        System.out.println("Setup before each test");
    }

    @Override
    public void afterEach(ExtensionContext context) {
        System.out.println("Cleanup after each test");
    }
}

@ExtendWith(SetupCleanupExtension.class)
public class SampleTest {

    @Test
    void testOne() {
        assertTrue(1 + 1 == 2);
    }

    @Test
    void testTwo() {
        assertTrue("hello".startsWith("h"));
    }
}

This code defines a class SetupCleanupExtension that implements BeforeEachCallback and AfterEachCallback. The beforeEach method prints a setup message before each test, and the afterEach method prints a cleanup message after each test.

The test class SampleTest uses @ExtendWith to register this extension. It contains two simple test methods with assertions that always pass.

When running the tests, the console will show the setup message before each test and the cleanup message after each test, demonstrating the callbacks work as expected.

Common Mistakes - 3 Pitfalls

Not registering the extension with @ExtendWith

Putting test logic inside the callback methods

Using System.out.println for important test verification

Bonus Challenge

Now add a data-driven test that runs the same test logic with three different input values using @ParameterizedTest

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