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🔌 Module 7 – API Testing with Playwright

Playwright is not just for UI testing. It has a built-in API testing engine that allows you to test REST APIs directly.

✅ Why Test APIs with Playwright?​

  • ⚡ Insanely Fast: API tests run in milliseconds compared to seconds/minutes for UI tests.
  • 🔗 End-to-End Validation: You can create data via API, verify it on the UI, and then delete it via API.
  • 🛠️ No Extra Tools: You don't need Postman or Axios; Playwright handles it with the built-in { request } fixture.

✅ The { request } Fixture​

Instead of { page } which launches a browser, API tests use { request } to make raw HTTP requests.

test('My API Test', async ({ request }) => {
  const response = await request.get('https://api.example.com/data');
});

✅ Complete API Test Suite​

Here is the code we wrote and executed successfully:

const { test, expect } = require('@playwright/test');

const BASE_URL = 'https://jsonplaceholder.typicode.com';

test.describe('API Testing with Playwright', () => {

  // 1. GET Request (Read)
  test('GET - Fetch all posts', async ({ request }) => {
    const response = await request.get(`${BASE_URL}/posts`);
    
    expect(response.status()).toBe(200);
    expect(response.ok()).toBeTruthy();
    
    const body = await response.json();
    expect(Array.isArray(body)).toBeTruthy();
    expect(body.length).toBeGreaterThan(0);
  });

  // 2. GET Request with Path Param (Read Single)
  test('GET - Fetch single post', async ({ request }) => {
    const response = await request.get(`${BASE_URL}/posts/1`);
    
    expect(response.status()).toBe(200);
    
    const body = await response.json();
    expect(body).toHaveProperty('id', 1);
    expect(body).toHaveProperty('title');
    expect(body).toHaveProperty('body');
  });

  // 3. POST Request (Create)
  test('POST - Create a new post', async ({ request }) => {
    const newPost = {
      title: 'Playwright API Testing',
      body: 'This is a test post created by Playwright',
      userId: 1
    };
    
    const response = await request.post(`${BASE_URL}/posts`, {
      data: newPost
    });
    
    expect(response.status()).toBe(201);
    
    const body = await response.json();
    expect(body.title).toBe(newPost.title);
    expect(body).toHaveProperty('id');
  });

  // 4. PUT Request (Update)
  test('PUT - Update a post', async ({ request }) => {
    const updatedPost = {
      id: 1,
      title: 'Updated Title',
      body: 'Updated body content',
      userId: 1
    };
    
    const response = await request.put(`${BASE_URL}/posts/1`, {
      data: updatedPost
    });
    
    expect(response.status()).toBe(200);
    
    const body = await response.json();
    expect(body.title).toBe(updatedPost.title);
  });

  // 5. DELETE Request (Delete)
  test('DELETE - Delete a post', async ({ request }) => {
    const response = await request.delete(`${BASE_URL}/posts/1`);
    expect(response.status()).toBe(200);
  });

});

✅ API Assertons Deep Dive​

When validating API responses, we can assert various parts of the payload:

AssertionExplanation
expect(response.status()).toBe(200)Asserts the HTTP status code
expect(response.ok()).toBeTruthy()Asserts status code is between 200-299
await response.json()Parses response body to JSON object
expect(body).toHaveProperty('key', value)Asserts field exists and matches value

🎯 Summary​

  • ✅ Playwright handles API testing natively using { request }.
  • ✅ You can easily perform GET, POST, PUT, DELETE methods.
  • ✅ API testing is perfect for fast, atomic validations before UI tests run.

🚀 Keep Going​

Apply what you learned in this module: