ASP.NET Core

Unit test using xUnit for a simple Calculator service:

public class Calculator
{
    public int Add(int a, int b) => a + b;
}

public class CalculatorTests
{
    [Fact]
    public void Add_ReturnsCorrectSum()
    {
        var calc = new Calculator();
        var result = calc.Add(2, 3);
        Assert.Equal(5, result);
    }
}

Integration test using WebApplicationFactory:

public class ApiTests : IClassFixture<WebApplicationFactory<Program>>
{
    private readonly HttpClient _client;

    public ApiTests(WebApplicationFactory<Program> factory)
    {
        _client = factory.CreateClient();
    }

    [Fact]
    public async Task GetEndpoint_ReturnsSuccess()
    {
        var response = await _client.GetAsync("/api/values");
        response.EnsureSuccessStatusCode();
        var content = await response.Content.ReadAsStringAsync();
        Assert.Contains("value1", content);
    }
}

Spring Boot

Unit test for a service:

@Service
public class CalculatorService {
    public int add(int a, int b) {
        return a + b;
    }
}

@SpringBootTest
public class CalculatorServiceTest {
    @Autowired
    CalculatorService service;

    @Test
    void testAdd() {
        assertEquals(5, service.add(2, 3));
    }
}

Express.js

Unit test using Jest:

// sum.js
function sum(a, b) {
  return a + b;
}
module.exports = sum;

// sum.test.js
const sum = require('./sum');

test('adds 2 + 3 to equal 5', () => {
  expect(sum(2, 3)).toBe(5);
});

Next.js

Unit test using React Testing Library:

import { render, screen } from '@testing-library/react';
import Button from '../components/Button';

test('renders button with text', () => {
  render(<Button>Click me</Button>);
  expect(screen.getByText('Click me')).toBeInTheDocument();
});

Flask

Integration test using Flask test client:

from flask import Flask
import unittest

app = Flask(__name__)

@app.route("/hello")
def hello():
    return "Hello World"

class FlaskTestCase(unittest.TestCase):
    def setUp(self):
        self.app = app.test_client()

    def test_hello(self):
        response = self.app.get('/hello')
        self.assertEqual(response.data, b'Hello World')

if __name__ == "__main__":
    unittest.main()

Laravel

Unit test using PHPUnit:

// app/Services/Calculator.php
namespace App\Services;
class Calculator {
    public function add($a, $b) { return $a + $b; }
}

// tests/Unit/CalculatorTest.php
namespace Tests\Unit;
use PHPUnit\Framework\TestCase;
use App\ServicesCalculator;

class CalculatorTest extends TestCase {
    public function testAdd() {
        $calc = new Calculator();
        $this->assertEquals(5, $calc->add(2, 3));
    }
}