Nested class lifecycle in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to use the correct annotation for a nested test class lifecycle.

JUnit

import org.junit.jupiter.api.*;

@TestInstance(TestInstance.Lifecycle.[1])
@Nested
class InnerTest {
    @Test
    void testMethod() {
        Assertions.assertTrue(true);
    }
}

Drag options to blanks, or click blank then click option'

APER_CLASS

BSINGLETON

CSTATIC

DPER_METHOD

Attempts:

3 left

💡 Hint

Common Mistakes

Using PER_CLASS lifecycle without understanding it creates one instance for all tests.

Confusing PER_METHOD with PER_CLASS lifecycle.

By default, nested test classes in JUnit use PER_METHOD lifecycle, which creates a new instance for each test method.

2fill in blank

medium

Complete the code to annotate a nested test class that shares the same instance for all tests.

JUnit

import org.junit.jupiter.api.*;

@TestInstance(TestInstance.Lifecycle.[1])
@Nested
class SharedInstanceTest {
    int counter = 0;

    @Test
    void testIncrement() {
        counter++;
        Assertions.assertTrue(counter > 0);
    }
}

Drag options to blanks, or click blank then click option'

ASTATIC

BPER_CLASS

CSINGLETON

DPER_METHOD

Attempts:

3 left

💡 Hint

Common Mistakes

Using PER_METHOD lifecycle which creates a new instance for each test, so state is not shared.

Confusing SINGLETON or STATIC which are not valid lifecycle options.

Using PER_CLASS lifecycle means the same instance of the nested test class is used for all test methods, allowing state sharing.

3fill in blank

hard

Fix the error in the nested test class lifecycle annotation to make the code compile.

JUnit

import org.junit.jupiter.api.*;

@TestInstance(TestInstance.Lifecycle.[1])
@Nested
class ErrorTest {
    @Test
    void testSomething() {
        Assertions.assertEquals(1, 1);
    }
}

Drag options to blanks, or click blank then click option'

APER_CLASS

BINSTANCE

CPER_METHOD

DSINGLETON

Attempts:

3 left

💡 Hint

Common Mistakes

Using invalid lifecycle values like INSTANCE or SINGLETON.

Misspelling lifecycle enum constants.

The option INSTANCE is invalid. The correct lifecycle options are PER_CLASS or PER_METHOD. Here, PER_CLASS is the fix to compile.

4fill in blank

hard

Fill both blanks to create a nested test class with a per-class lifecycle and a setup method that runs once before all tests.

JUnit

import org.junit.jupiter.api.*;

@TestInstance(TestInstance.Lifecycle.[1])
@Nested
class SetupTest {

    @Before[2]
    void init() {
        System.out.println("Setup before all tests");
    }

    @Test
    void testOne() {
        Assertions.assertTrue(true);
    }
}

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APER_CLASS

BPER_METHOD

CAll

DEach

Attempts:

3 left

💡 Hint

Common Mistakes

Using PER_METHOD lifecycle with non-static @BeforeAll causes errors.

Using @BeforeEach instead of @BeforeAll for setup before all tests.

Using PER_CLASS lifecycle allows the use of @BeforeAll on non-static methods in nested classes.

5fill in blank

hard

Fill all three blanks to define a nested test class with per-class lifecycle, a non-static @BeforeAll method, and a test method that asserts a counter increments.

JUnit

import org.junit.jupiter.api.*;

@TestInstance(TestInstance.Lifecycle.[1])
@Nested
class CounterTest {
    int counter = 0;

    @Before[2]
    void setup() {
        counter = 1;
    }

    @Test
    void testIncrement() {
        counter[3];
        Assertions.assertEquals(2, counter);
    }
}

Drag options to blanks, or click blank then click option'

APER_METHOD

BPER_CLASS

C++

DAll

Attempts:

3 left

💡 Hint

Common Mistakes

Using PER_METHOD lifecycle with non-static @BeforeAll causes errors.

Using -- instead of ++ causing the counter to decrease.

Using @BeforeEach instead of @BeforeAll for setup before all tests.

With PER_CLASS lifecycle, @BeforeAll can be non-static. The counter is incremented with ++ to reach 2.