@AfterEach method in JUnit - Test Execution Trace

Test Overview

This test demonstrates the use of the @AfterEach method in JUnit. It verifies that a resource is properly reset after each test method runs.

Test Code - JUnit 5

JUnit

import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;

public class CounterTest {
    private Counter counter = new Counter();

    @BeforeEach
    void setUp() {
    }

    @AfterEach
    void reset() {
        counter.reset();
    }

    @Test
    void testIncrement() {
        counter.increment();
        assertEquals(1, counter.getValue());
    }

    @Test
    void testDecrement() {
        counter.decrement();
        assertEquals(-1, counter.getValue());
    }
}

class Counter {
    private int value = 0;

    void increment() {
        value++;
    }

    void decrement() {
        value--;
    }

    int getValue() {
        return value;
    }

    void reset() {
        value = 0;
    }
}

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test framework initializes and calls setUp() before testIncrement()	Counter value is 0 (initial state)	-	PASS
2	testIncrement() calls counter.increment()	Counter value increases from 0 to 1	assertEquals(1, counter.getValue()) verifies value is 1	PASS
3	After testIncrement(), reset() is called by @AfterEach	Counter value resets from 1 to 0	-	PASS
4	Test framework initializes and calls setUp() before testDecrement()	Counter value is 0 (from previous reset)	-	PASS
5	testDecrement() calls counter.decrement()	Counter value decreases from 0 to -1	assertEquals(-1, counter.getValue()) verifies value is -1	PASS
6	After testDecrement(), reset() is called by @AfterEach	Counter value resets from -1 to 0	-	PASS

Failure Scenario

Failing Condition: If the reset() method is missing or does not reset the counter value, the counter state will carry over between tests.

Execution Trace Quiz - 3 Questions

What is the purpose of the @AfterEach method in this test?

A To run the test methods in order

B To initialize the counter before each test

C To reset the counter after each test method runs

D To assert the counter value

Key Result

Using @AfterEach ensures that any changes made during a test are cleaned up, keeping tests independent and reliable.