Custom extensions in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to register a custom JUnit 5 extension using the @ExtendWith annotation.

JUnit

@ExtendWith([1].class)
public class MyTest {
    @Test
    void testSomething() {
        // test code
    }
}

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AJUnitExtension

BTestExtension

CExtensionPoint

DMyExtension

Attempts:

3 left

💡 Hint

Common Mistakes

Using a class name that does not exist as an extension.

Forgetting to add .class after the extension class name.

The @ExtendWith annotation requires the class name of the custom extension. Here, 'MyExtension' is the correct custom extension class.

2fill in blank

medium

Complete the code to implement a custom JUnit 5 extension by overriding the beforeEach method.

JUnit

public class MyExtension implements BeforeEachCallback {
    @Override
    public void [1](ExtensionContext context) throws Exception {
        System.out.println("Before each test");
    }
}

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AbeforeEach

BbeforeAll

CafterEach

DafterAll

Attempts:

3 left

💡 Hint

Common Mistakes

Using afterEach instead of beforeEach.

Using beforeAll which belongs to a different interface.

The BeforeEachCallback interface requires implementing the beforeEach method to run code before each test.

3fill in blank

hard

Fix the error in the custom extension code by completing the missing method name.

JUnit

public class MyExtension implements AfterTestExecutionCallback {
    @Override
    public void [1](ExtensionContext context) throws Exception {
        System.out.println("After test execution");
    }
}

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AafterTestExecution

BafterAll

CafterEach

DbeforeTestExecution

Attempts:

3 left

💡 Hint

Common Mistakes

Using afterEach which belongs to a different interface.

Using beforeTestExecution which is not part of this interface.

The AfterTestExecutionCallback interface requires the method afterTestExecution to be implemented.

4fill in blank

hard

Fill both blanks to create a custom extension that implements both BeforeAllCallback and AfterAllCallback interfaces.

JUnit

public class MyExtension implements [1], [2] {
    @Override
    public void beforeAll(ExtensionContext context) throws Exception {
        System.out.println("Before all tests");
    }

    @Override
    public void afterAll(ExtensionContext context) throws Exception {
        System.out.println("After all tests");
    }
}

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ABeforeAllCallback

BBeforeEachCallback

CAfterAllCallback

DAfterEachCallback

Attempts:

3 left

💡 Hint

Common Mistakes

Using BeforeEachCallback or AfterEachCallback which run before/after each test, not all tests.

Forgetting to implement both interfaces.

To run code before all tests and after all tests, implement BeforeAllCallback and AfterAllCallback interfaces.

5fill in blank

hard

Fill all three blanks to create a custom extension that logs test start and end times using BeforeTestExecutionCallback and AfterTestExecutionCallback.

JUnit

public class TimingExtension implements [1], [2] {
    private long startTime;

    @Override
    public void beforeTestExecution(ExtensionContext context) throws Exception {
        startTime = System.currentTimeMillis();
        System.out.println("Test started at: " + startTime);
    }

    @Override
    public void [3](ExtensionContext context) throws Exception {
        long endTime = System.currentTimeMillis();
        System.out.println("Test ended at: " + endTime);
        System.out.println("Duration: " + (endTime - startTime) + " ms");
    }
}

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ABeforeTestExecutionCallback

BAfterTestExecutionCallback

CafterTestExecution

DbeforeTestExecution

Attempts:

3 left

💡 Hint

Common Mistakes

Using beforeTestExecution as the method name for after test execution.

Not implementing both interfaces.

The class implements BeforeTestExecutionCallback and AfterTestExecutionCallback interfaces. The method afterTestExecution is overridden to log the end time.