Contoh 1: Test Simple Calculation

File: src/main/java/com/example/Calculator.java

package com.example;

public class Calculator {
    
    public int add(int a, int b) {
        return a + b;
    }
    
    public int subtract(int a, int b) {
        return a - b;
    }
    
    public int multiply(int a, int b) {
        return a * b;
    }
    
    public int divide(int a, int b) {
        if (b == 0) throw new IllegalArgumentException("Cannot divide by zero");
        return a / b;
    }
    
    public boolean isEven(int n) {
        return n % 2 == 0;
    }
}

File: src/test/java/com/example/TestCalculator.java

package com.example;

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

public class TestCalculator {
    
    private Calculator calc;
    
    @BeforeEach
    public void setup() {
        calc = new Calculator();
    }
    
    @Test
    public void testAdd() {
        assertEquals(5, calc.add(2, 3));
        System.out.println("✅ testAdd passed");
    }
    
    @Test
    public void testSubtract() {
        assertEquals(2, calc.subtract(5, 3));
        System.out.println("✅ testSubtract passed");
    }
    
    @Test
    public void testMultiply() {
        assertEquals(12, calc.multiply(3, 4));
        System.out.println("✅ testMultiply passed");
    }
    
    @Test
    public void testDivide() {
        assertEquals(2, calc.divide(6, 3));
        System.out.println("✅ testDivide passed");
    }
    
    @Test
    public void testDivideByZero() {
        assertThrows(IllegalArgumentException.class, () -> {
            calc.divide(10, 0);
        });
        System.out.println("✅ testDivideByZero passed");
    }
    
    @Test
    public void testIsEven() {
        assertTrue(calc.isEven(4));
        assertFalse(calc.isEven(5));
        System.out.println("✅ testIsEven passed");
    }
}

Cara Jalankan

Option 1: Klik Right-Click di file → “Run Tests”

VSCode akan menjalankan semua test methods dan show hasil.

Option 2: Gunakan Terminal

mvn test -Dtest=TestCalculator

Expected Output

✅ testAdd passed
✅ testSubtract passed
✅ testMultiply passed
✅ testDivide passed
✅ testDivideByZero passed
✅ testIsEven passed

Tests run: 6, Failures: 0, Skipped: 0, Time elapsed: 0.xxx s

---

Contoh 2: Test dengan Setup dan Cleanup

File: src/test/java/com/example/TestWithSetup.java

package com.example;

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

public class TestWithSetup {
    
    private List<String> list;
    
    @BeforeEach
    public void setup() {
        list = new ArrayList<>();
        System.out.println("Setup: List created");
    }
    
    @Test
    public void testAddItem() {
        list.add("Apple");
        assertEquals(1, list.size());
        System.out.println("  ✅ testAddItem passed");
    }
    
    @Test
    public void testRemoveItem() {
        list.add("Apple");
        list.add("Banana");
        list.remove("Apple");
        assertEquals(1, list.size());
        System.out.println("  ✅ testRemoveItem passed");
    }
    
    @Test
    public void testListEmpty() {
        assertTrue(list.isEmpty());
        System.out.println("  ✅ testListEmpty passed");
    }
    
    @AfterEach
    public void cleanup() {
        list = null;
        System.out.println("Cleanup: List cleared\n");
    }
}

Output:

Setup: List created
  ✅ testAddItem passed
Cleanup: List cleared

Setup: List created
  ✅ testRemoveItem passed
Cleanup: List cleared

Setup: List created
  ✅ testListEmpty passed
Cleanup: List cleared

Tests run: 3, Failures: 0

Perhatikan: Setup dan cleanup dipanggil 3 kali untuk 3 test methods.