Playwright is a test automation library by Microsoft that facilitates the automation of web applications across multiple browsers. The guide covers its installation, features such as cross-browser testing, automatic waiting, network interception, and the flexible test execution architecture. It aims to provide developers and testers with the tools to create reliable, efficient, and scalable automated tests to enhance application quality.

2. Playwright For Test Automation : A
Step by Step Guide
Playwright is a powerful and versatile automation library developed by Microsoft. It enables
developers and testers to automate web applications across multiple browsers with ease. This
guide will walk you through the basics of using Playwright for test automation, from installation
to writing and running your first tests. Playwright automation supports Chromium, Firefox, and
WebKit, allowing you to test across different browsers.
In this blog, we will deep dive into the various features of Playwright and how we can perform
end-to-end testing with Playwright with detailed examples.
Key Features of Playwright
Below are some of the key feature of Playwright testing tool
1. Cross-browser Testing: Playwright supports all major browsers out of the box,
including Chromium, Firefox, and WebKit (Safari). This cross-browser support allows you
to write tests once and run them across multiple browsers without any additional

3. configuration or setup. Playwright ensures consistent behavior and API across all
supported browsers, making it easier to maintain and scale your test suite. Playwright
provides built-in support for device emulation using browsers like Safari ,chrome.
2. Headless and Headful Modes: Playwright allows you to run tests in headless mode
(without a visible browser window) or headful mode (with a visible browser window).
Headless mode is useful for running tests in CI/CD pipelines. Headful mode is beneficial
for debugging, visual inspection, or when you need to interact with the browser during
test execution.
3. Automatic Waiting: Playwright automatically waits for elements to be ready before
interacting with them, reducing the risk of test flakiness caused by timing issues. It
employs intelligent waiting strategies, such as waiting for network requests to complete
or DOM mutations to occur, ensuring that tests are executed reliably and consistently.
4. Network Interception: Playwright provides powerful network interception capabilities,
allowing you to intercept and modify network requests and responses during test
execution. This feature is useful for testing scenarios involving APIs, mocking responses,
simulating network conditions, or bypassing authentication mechanisms.
5. Multiple Contexts: Playwright allows you to create multiple browser contexts within a
single test run, effectively simulating different user sessions or environments. This
feature is particularly useful for testing scenarios involving multi-user interactions, such
as chat applications or collaborative tools.
6. Powerful Selectors: Playwright offers a rich set of selector strategies, including CSS
selectors, XPath, text selectors, and more. It also provides advanced selector options,
such as handling dynamic elements, selecting elements based on their visibility or
accessibility, and selecting elements within iframes and shadow DOMs, which are
common in modern web applications.
7. Screenshot and Video Capture: Playwright enables you to capture screenshots and
record videos of your test runs with a single line of code. This feature is invaluable for
debugging, visual regression testing, and generating visual artifacts for documentation or
reporting purposes.
8. Isolation and Parallelism: Playwright provides built-in support for running tests in
isolation and in parallel. Test isolation ensures that each test run is independent and
doesn’t interfere with other tests, preventing state pollution and improving test reliability.
Parallel test execution can significantly speed up your test suite by utilizing multiple CPU
cores or machines, reducing overall test execution time.

4. Playwright Test Automation Framework
Playwright’s architecture is designed to provide a robust, flexible, and high-performance
framework for browser automation. Its support for multiple browser engines, isolated browser
contexts, and powerful API makes it an excellent choice for web scraping, automated testing,
and other browser automation tasks. The architecture ensures that tests and scripts are reliable,
efficient, and easy to maintain.
Key Components and Processes
1. Client Side (Automation Scripts):
○ Languages Supported: Playwright supports JavaScript and TypeScript
“natively”, while also providing “bindings” for Java, Python, and C# for writing
automation scripts.
○ Test Script Creation: Users write test scripts in their preferred language. These
scripts include test cases, interaction commands, and assertions. JSON is often
used for configuration and data exchange.
2. WebSocket Connection:
● Handshake: When a test script is executed, it initiates a connection to the Playwright
server (Node.js). This connection involves an initial handshake to establish
communication.
● Full Duplex (Bi-Directional) Communication: Once connected, there is a bi-directional
communication channel between the client and the server. This is essential for sending
commands to the browser and receiving responses or events in real time.
● Open and Persistent Connection: The WebSocket connection remains open and
persistent throughout the session, allowing continuous interaction between the test
scripts and the browser.
● Connection Closure: After test execution, the connection can be closed either by the
client or the server, marking the end of the session.
3. Server Side (Node.js):
● Node.js Server: The server side is managed by a Node.js application, which
orchestrates the interaction between the client scripts and the browsers.

5. ● Handling Commands and Events: The Node.js server receives commands from the
client, processes them, and sends appropriate instructions to the browsers. It also listens
for events from the browser and relays them back to the client.
4. Browser Automation (CDP and CDP+):
● CDP (Chrome DevTools Protocol): Playwright utilizes the CDP for interacting with
Chromium-based browsers. CDP manages the render, browser, and network processes,
which are essential for rendering pages, managing browser sessions, and handling
network interactions.
● CDP+: The image also mentions CDP+ for browsers like Firefox and WebKit (Safari).
Playwright extends support to these browsers by using protocols similar to CDP,
ensuring a consistent API across different browsers. Each browser process (render,
browser, network) is managed to simulate user interactions accurately.
How Playwright Test Execution Work:
1. The client (test script) sends instructions to the server over the WebSocket connection.
2. The server receives these instructions and translates them into commands that can be
understood by the browser instances.
3. The server communicates with the browser instances using either CDP or CDP+,
depending on the requirements.
4. The browser instances execute the commands, such as navigating to web pages,
interacting with elements, or capturing screenshots.
5. The results or data from the browser instances are sent back to the server.
6. The server relays the results or data back to the client over the WebSocket connection.
Conclusion
Playwright offers a powerful and versatile framework for test automation, making it a valuable
tool for developers and testers alike. Its ability to handle multiple browsers, provide
cross-platform support, and offer rich APIs for interaction and validation makes it stand out in
the test automation landscape. By following the step-by-step guide, users can leverage

6. Playwright’s capabilities to create reliable, efficient, and scalable automated tests, ultimately
enhancing the quality and performance of their applications. Embracing Playwright can
streamline testing processes, reduce manual effort, and ensure a more robust and seamless
user experience.
Source: This article was originally published at testgrid.io.