Verify resource cleanup after each test using @AfterEach

Preconditions (2)

Step 1: Create a test class with two test methods that open a resource (e.g., a list)

Step 2: In each test method, add an item to the resource

Step 3: Add an @AfterEach method that clears the resource after each test

Step 4: Run the tests

✅ Expected Result: After each test method runs, the resource is cleared so that the next test starts with an empty resource

Automation Requirements - JUnit 5

Assertions Needed:

Verify the resource is empty at the start of each test

Verify the resource contains the expected item after adding

Verify the resource is cleared after each test via @AfterEach

Best Practices:

Use @BeforeEach to initialize resources if needed

Use @AfterEach to clean up resources to avoid test interference

Use assertions from org.junit.jupiter.api.Assertions

Keep test methods independent

Automated Solution

JUnit

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

public class ResourceCleanupTest {
    private List<String> resource;

    @BeforeEach
    void setUp() {
        resource = new ArrayList<>();
        assertTrue(resource.isEmpty(), "Resource should be empty before each test");
    }

    @Test
    void testAddItemOne() {
        resource.add("item1");
        assertEquals(1, resource.size(), "Resource should contain one item");
        assertTrue(resource.contains("item1"), "Resource should contain 'item1'");
    }

    @Test
    void testAddItemTwo() {
        resource.add("item2");
        assertEquals(1, resource.size(), "Resource should contain one item");
        assertTrue(resource.contains("item2"), "Resource should contain 'item2'");
    }

    @AfterEach
    void tearDown() {
        resource.clear();
        assertTrue(resource.isEmpty(), "Resource should be empty after each test");
    }
}

This test class demonstrates the use of @AfterEach in JUnit 5 to clean up resources after each test method.

setUp() method annotated with @BeforeEach initializes the resource and asserts it is empty before each test.

Two test methods add different items to the resource and verify the additions.

The @AfterEach method tearDown() clears the resource and asserts it is empty after each test, ensuring no leftover data affects other tests.

This pattern keeps tests independent and avoids side effects.

Common Mistakes - 3 Pitfalls

Not clearing or resetting shared resources after each test

Using @AfterAll instead of @AfterEach for cleanup

Modifying resources in @AfterEach without proper initialization in @BeforeEach

Bonus Challenge

Now add a third test method that adds two items and verify the resource is still cleared after the test

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