Understanding Playwright API and how to define a framework in typescript

 

Unified API and UI Testing

• Playwright uses a single framework and runner (@playwright/test) for both API tests and End-to-End (UI) tests. This allows for easily mixing them together.

Playwright Provides Built-in APIRequestContext fixture

• Playwright provides a dedicated request fixture that abstracts the HTTP client logic.
• It supports all the HTTP methods.
• The APIRequestContext can be created with cookies, headers, and authentication tokens that are automatically attached to all requests made within that context.
• The API methods allow fine-grained control over request parameters, including headers, JSON/form data, and multipart file uploads, all through structured configuration objects.

static async login(request: APIRequestContext, body: LoginRequest) {
    const response = await request.post(ENV.baseURL +'/login', {
    headers: {
      'x-api-key': ENV.apiKey,
      'Content-Type': 'application/json'
    },
      data: body,
    });

    const parsed: LoginResponse = await response.json();
    return { response, parsed };
  } 

//above LoginRequest defines the body of the request
export interface LoginRequest {
  email: string;
  password: string;
}

await api.post('/upload', {
  multipart: { file: fs.createReadStream('./image.png') }
});

JSON Body Handling is Extremely Easy

• No need for external libraries (e.g., Gson, Jackson like in Rest Assured).
• Playwright automatically convert the response into data object

A basic flow of Request and Response in Playwright API

Assertions in Playwright API:

Schema Validators:

• Defines the rules for the structure, data types, and constraints of API responses, ensuring the API contract is strictly followed
• Schema Validator verifies that the actual data returned by the API matches the expected format
• Services often call schema validation immediately after receiving and parsing a successful API response.