BeforeEachCallback and AfterEachCallback in JUnit - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of BeforeEachCallback in JUnit 5

What is the main purpose of implementing the BeforeEachCallback interface in a JUnit 5 extension?

A To execute code only if a test fails

B To execute code once before all tests in a test class run

C To execute code after each test method runs

D To execute code before each individual test method runs

💡 Hint

Think about when you want to prepare the test environment for every test method.

BeforeEachCallback runs code before each test method, allowing setup specific to each test.

🧠 Conceptual

intermediate

Difference between BeforeEachCallback and AfterEachCallback

Which statement correctly describes the difference between BeforeEachCallback and AfterEachCallback in JUnit 5?

A BeforeEachCallback runs before each test; AfterEachCallback runs after each test

B BeforeEachCallback runs after each test; AfterEachCallback runs before each test

C Both run before each test but in different threads

D Both run after all tests have finished

💡 Hint

Think about setup and cleanup around each test.

BeforeEachCallback runs before each test method; AfterEachCallback runs after each test method.

❓ Predict Output

advanced

Output of JUnit Extension with BeforeEachCallback and AfterEachCallback

Given the following JUnit 5 extension code, what will be printed to the console when running a test method using this extension?

JUnit

import org.junit.jupiter.api.extension.*;

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

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

// Test class uses @ExtendWith(MyExtension.class) and has one test method that prints "Running test"

A Setup before test\nRunning test\nCleanup after test

B Cleanup after test\nSetup before test\nRunning test

C Setup before test\nCleanup after test\nRunning test

D Running test\nSetup before test\nCleanup after test

💡 Hint

Remember the order: beforeEach runs before the test, afterEach runs after.

The extension prints before the test method runs, then the test prints, then afterEach prints.

🔧 Debug

advanced

Identify the error in this AfterEachCallback implementation

What error will occur when running this JUnit 5 extension code implementing AfterEachCallback?

JUnit

import org.junit.jupiter.api.extension.*;

public class FaultyExtension implements AfterEachCallback {
    @Override
    public void afterEach() {
        System.out.println("Cleaning up");
    }
}

A No error, code runs fine

B Runtime NullPointerException

C Compilation error: method afterEach() does not override or implement a method from a supertype

D Test fails with IllegalStateException

💡 Hint

Check the method signature required by AfterEachCallback interface.

The afterEach method must accept an ExtensionContext parameter; missing it causes a compile error.

❓ framework

expert

Correct usage of BeforeEachCallback and AfterEachCallback in a JUnit 5 extension

Which code snippet correctly implements both BeforeEachCallback and AfterEachCallback interfaces in a JUnit 5 extension to print messages before and after each test method?

A

public class Ext implements BeforeEachCallback, AfterEachCallback {
    public void beforeEach() {
        System.out.println("Before");
    }
    public void afterEach() {
        System.out.println("After");
    }
}

B

public class Ext implements BeforeEachCallback, AfterEachCallback {
    @Override
    public void beforeEach(ExtensionContext context) {
        System.out.println("Before");
    }
    @Override
    public void afterEach(ExtensionContext context) {
        System.out.println("After");
    }
}

C

public class Ext implements BeforeEachCallback, AfterEachCallback {
    @Override
    public void beforeEach() {
        System.out.println("Before");
    }
    @Override
    public void afterEach() {
        System.out.println("After");
    }
}

D

public class Ext implements BeforeEachCallback, AfterEachCallback {
    public void beforeEach(ExtensionContext context) {
        System.out.println("Before");
    }
    public void afterEach(ExtensionContext context) {
        System.out.println("After");
    }
}

💡 Hint

Check method signatures and use of @Override annotations.

Correct implementation requires method signatures with ExtensionContext parameter and @Override annotations.