Execution order of lifecycle methods in JUnit - Build an Automation Script

Verify the execution order of JUnit lifecycle methods

Preconditions (2)

Step 1: Create a test class with methods annotated with @BeforeAll, @BeforeEach, @Test, @AfterEach, and @AfterAll

Step 2: Add print statements in each lifecycle method to log their execution

Step 3: Run the test class

Step 4: Observe the console output for the order of method execution

✅ Expected Result: The console output shows the lifecycle methods executing in this order: @BeforeAll once, @BeforeEach before each test, @Test methods, @AfterEach after each test, and @AfterAll once at the end

Automation Requirements - JUnit 5

Assertions Needed:

Verify that @BeforeAll method runs once before all tests

Verify that @BeforeEach method runs before each test method

Verify that @AfterEach method runs after each test method

Verify that @AfterAll method runs once after all tests

Best Practices:

Use @TestInstance(Lifecycle.PER_CLASS) to allow non-static @BeforeAll and @AfterAll methods

Use assertions to confirm the order of execution

Avoid using Thread.sleep; rely on proper test lifecycle hooks

Keep test methods independent and isolated

Automated Solution

JUnit

import org.junit.jupiter.api.*;
import java.util.ArrayList;
import java.util.List;
import static org.junit.jupiter.api.Assertions.*;

@TestInstance(TestInstance.Lifecycle.PER_CLASS)
public class LifecycleOrderTest {

    private final List<String> executionOrder = new ArrayList<>();

    @BeforeAll
    void beforeAll() {
        executionOrder.add("BeforeAll");
    }

    @BeforeEach
    void beforeEach() {
        executionOrder.add("BeforeEach");
    }

    @Test
    void testOne() {
        executionOrder.add("TestOne");
    }

    @Test
    void testTwo() {
        executionOrder.add("TestTwo");
    }

    @AfterEach
    void afterEach() {
        executionOrder.add("AfterEach");
    }

    @AfterAll
    void afterAll() {
        executionOrder.add("AfterAll");

        // Now verify the order
        // Expected order:
        // BeforeAll
        // BeforeEach, TestOne, AfterEach
        // BeforeEach, TestTwo, AfterEach
        // AfterAll

        List<String> expectedOrder = List.of(
            "BeforeAll",
            "BeforeEach", "TestOne", "AfterEach",
            "BeforeEach", "TestTwo", "AfterEach",
            "AfterAll"
        );

        assertEquals(expectedOrder, executionOrder, "Lifecycle methods did not execute in expected order");
    }
}

This test class uses JUnit 5 lifecycle annotations to track the order of method execution.

We use a list executionOrder to record each lifecycle method call.

@BeforeAll runs once before all tests, so it adds "BeforeAll" first.

@BeforeEach runs before each test method, so it adds "BeforeEach" before each test.

Each @Test method adds its own name to the list.

@AfterEach runs after each test method, adding "AfterEach".

@AfterAll runs once after all tests, adding "AfterAll" and then asserting the entire order matches the expected sequence.

We use @TestInstance(Lifecycle.PER_CLASS) to allow non-static @BeforeAll and @AfterAll methods for simplicity.

This approach confirms the lifecycle methods execute in the correct order by checking the list contents at the end.

Common Mistakes - 4 Pitfalls

{'mistake': 'Making @BeforeAll and @AfterAll methods non-static without using @TestInstance(PER_CLASS)', 'why_bad': "JUnit 5 requires @BeforeAll and @AfterAll to be static unless the test instance lifecycle is PER_CLASS, otherwise tests won't run correctly.", 'correct_approach': 'Use @TestInstance(TestInstance.Lifecycle.PER_CLASS) to allow non-static lifecycle methods or make them static.'}

Not verifying the execution order with assertions

Using print statements only without automated checks

Modifying shared state without isolation between tests

Bonus Challenge

Now add data-driven testing with 3 different test methods to verify lifecycle order for each

Show Hint

Practice

1. In JUnit 5, which lifecycle method runs exactly once before any test methods in the class?

easy

A. @AfterAll

B. @BeforeEach

C. @AfterEach

D. @BeforeAll

Solution

1. Step 1: Understand lifecycle annotations

   @BeforeAll is designed to run once before all tests in the class.

2. Step 2: Compare with other annotations

   @BeforeEach runs before each test, @AfterEach after each test, and @AfterAll once after all tests.

3. Final Answer:

   @BeforeAll -> Option D

4. Quick Check:

   @BeforeAll runs once before all tests [OK]

Hint: Remember: All = once before all tests [OK]

Common Mistakes:

• Confusing @BeforeEach with @BeforeAll
• Thinking @AfterAll runs before tests
• Mixing up @AfterEach and @BeforeEach

2. Which of the following is the correct syntax to define a method that runs after each test in JUnit 5?

easy

A. @AfterEach
void cleanup() {}

B. @AfterAll
void cleanup() {}

C. @BeforeEach
void cleanup() {}

D. @BeforeAll
void cleanup() {}

Solution

1. Step 1: Identify the annotation for after each test

   @AfterEach is the annotation that runs a method after every test method.

2. Step 2: Check method syntax

   The method should be void and can have any name, here 'cleanup()' is valid.

3. Final Answer:

   @AfterEach void cleanup() {} -> Option A

4. Quick Check:

   @AfterEach runs after each test method [OK]

Hint: AfterEach means after every single test method [OK]

Common Mistakes:

• Using @AfterAll instead of @AfterEach
• Confusing @BeforeEach with @AfterEach
• Missing void return type

3. Consider the following JUnit 5 test class:

@BeforeAll
static void initAll() { System.out.println("InitAll"); }
@BeforeEach
void init() { System.out.println("Init"); }
@Test
void testOne() { System.out.println("TestOne"); }
@Test
void testTwo() { System.out.println("TestTwo"); }
@AfterEach
void tearDown() { System.out.println("TearDown"); }
@AfterAll
static void tearDownAll() { System.out.println("TearDownAll"); }

What is the correct order of printed lines when running this test class?

medium

A. InitAll, Init, TestOne, TearDown, Init, TestTwo, TearDown, TearDownAll

B. Init, InitAll, TestOne, TearDown, TestTwo, Init, TearDownAll

C. InitAll, Init, TestOne, Init, TestTwo, TearDown, TearDownAll, TearDown

D. InitAll, TestOne, Init, TearDown, Init, TestTwo, TearDown, TearDownAll

Solution

1. Step 1: Understand lifecycle method order

   @BeforeAll runs once before all tests, then for each test @BeforeEach runs, test runs, then @AfterEach runs. Finally, @AfterAll runs once after all tests.

2. Step 2: Apply to given methods

   Output order: InitAll (once), then for testOne: Init, TestOne, TearDown; for testTwo: Init, TestTwo, TearDown; finally TearDownAll.

3. Final Answer:

   InitAll, Init, TestOne, TearDown, Init, TestTwo, TearDown, TearDownAll -> Option A

4. Quick Check:

   BeforeAll once, BeforeEach-Test-AfterEach per test, AfterAll once [OK]

Hint: Remember: BeforeAll/AfterAll once, BeforeEach/AfterEach per test [OK]

Common Mistakes:

• Mixing order of BeforeAll and BeforeEach
• Forgetting AfterEach runs after each test
• Placing AfterAll before AfterEach

4. Given the following JUnit 5 test class snippet, identify the error:

@BeforeAll
void setupAll() { System.out.println("Setup all"); }
@Test
void testMethod() { System.out.println("Test"); }

What is the problem with this code?

medium

A. @BeforeAll method must return boolean.

B. @BeforeAll method must be static.

C. @BeforeAll method cannot have a body.

D. @BeforeAll method must be private.

Solution

1. Step 1: Recall @BeforeAll requirements

   In JUnit 5, @BeforeAll methods must be static unless using a test instance lifecycle that allows non-static.

2. Step 2: Check method signature

   The method 'setupAll' is not static, which causes a runtime error or test failure.

3. Final Answer:

   @BeforeAll method must be static. -> Option B

4. Quick Check:

   @BeforeAll requires static method by default [OK]

Hint: @BeforeAll methods are static unless configured otherwise [OK]

Common Mistakes:

• Making @BeforeAll non-static without lifecycle config
• Assuming @BeforeAll can be private
• Thinking @BeforeAll must return a value

5. You want to open a database connection once before all tests and close it once after all tests in a JUnit 5 test class. You also want to reset some data before each test and clean up after each test. Which combination of lifecycle methods should you use?

hard

A. @BeforeAll for resetting data, @AfterAll for cleanup, @BeforeEach for opening connection, @AfterEach for closing connection

B. @BeforeEach for opening connection, @AfterEach for closing connection, @BeforeAll for resetting data, @AfterAll for cleanup

C. @BeforeAll for opening connection, @AfterAll for closing connection, @BeforeEach for resetting data, @AfterEach for cleanup

D. @BeforeEach for resetting data, @AfterEach for cleanup, @BeforeAll for opening connection, @AfterAll for closing connection

Solution

1. Step 1: Assign tasks to lifecycle methods

   Opening and closing the database connection should happen once, so use @BeforeAll and @AfterAll.

2. Step 2: Use per-test methods for data reset and cleanup

   Resetting data and cleaning up should happen before and after each test, so use @BeforeEach and @AfterEach.

3. Final Answer:

   @BeforeAll for opening connection, @AfterAll for closing connection, @BeforeEach for resetting data, @AfterEach for cleanup -> Option C

4. Quick Check:

   Once methods for setup/teardown, each methods for per-test tasks [OK]

Hint: Once = BeforeAll/AfterAll, each test = BeforeEach/AfterEach [OK]

Common Mistakes:

• Opening connection before each test unnecessarily
• Resetting data only once before all tests
• Closing connection after each test causing overhead