Test independence in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to mark the test method as independent in JUnit 5.

JUnit

import org.junit.jupiter.api.Test;

public class CalculatorTest {

    @[1]
    void testAddition() {
        // test code here
    }
}

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ABeforeEach

BDisabled

CAfterEach

DTest

Attempts:

3 left

💡 Hint

Common Mistakes

Using @BeforeEach or @AfterEach instead of @Test

Forgetting to add any annotation

The @Test annotation marks a method as a test method in JUnit 5. Each test method runs independently.

2fill in blank

medium

Complete the code to ensure each test method runs with a fresh Calculator instance.

JUnit

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class CalculatorTest {
    Calculator calculator;

    @BeforeEach
    void [1]() {
        calculator = new Calculator();
    }

    @Test
    void testAddition() {
        // test code here
    }
}

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Asetup

Binitialize

CbeforeAll

Dreset

Attempts:

3 left

💡 Hint

Common Mistakes

Using @BeforeAll instead of @BeforeEach

Naming the method something unrelated

The method annotated with @BeforeEach runs before each test method. Naming it setup is a common convention.

3fill in blank

hard

Fix the error in the test method to ensure test independence by avoiding shared state.

JUnit

import org.junit.jupiter.api.Test;

public class CounterTest {
    static int count = 0;

    @Test
    void testIncrement() {
        count++;
        assertEquals(1, [1]);
    }
}

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ACounterTest.count

Bthis.count

Ccount

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using instance variable syntax for static variable

Asserting wrong expected value

The test checks the static variable count. Using count directly is correct. However, static state causes tests to depend on each other, which is bad practice.

4fill in blank

hard

Fill both blanks to create independent tests by resetting shared state before each test.

JUnit

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class SharedResourceTest {
    static int resourceCount = 0;

    @BeforeEach
    void [1]() {
        resourceCount = [2];
    }

    @Test
    void testOne() {
        resourceCount++;
        assertEquals(1, resourceCount);
    }

    @Test
    void testTwo() {
        resourceCount += 2;
        assertEquals(2, resourceCount);
    }
}

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Areset

Binitialize

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Not resetting the static variable

Setting the variable to 1 instead of 0

The @BeforeEach method named reset sets resourceCount to 0 before each test, ensuring tests do not affect each other.

5fill in blank

hard

Fill all three blanks to write independent tests using instance variables and proper setup.

JUnit

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;

public class BankAccountTest {
    BankAccount [1];

    @BeforeEach
    void [2]() {
        [1] = new BankAccount();
    }

    @Test
    void testDeposit() {
        [1].deposit(100);
        assertEquals(100, [1].getBalance());
    }
}

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Aaccount

Bsetup

Cbalance

Dinitialize

Attempts:

3 left

💡 Hint

Common Mistakes

Using static variables instead of instance variables

Not initializing the object before tests

Using an instance variable account and initializing it in a setup method before each test ensures tests are independent and do not share state.