Being a test engineer (QA) for a decade «I’ve seen things you people wouldn’t believe», I’ve tested enough web applications to accumulate experience that can be shared. I collected tricky test cases which somehow led to bugs and hacks to perform unusual checks. They are sorted by logical blocks in…

When a frontend team starts building a testing infrastructure, there is always a debate about the choice of testing tools. — There are dozens of tools for testing web applications on JavaScript, TypeScript and Node.js. Ava — test runner; CodeceptJS — end-to-end testing framework; Cypress — end-to-end browser testing framework; Hermione — test runner for browser testing based on Mocha and WebdriverIO;

While working on test automation in different projects, I’ve learned that there are not enough static analyzers and code formatters for writing good tests. The team had to have an agreement on how the tests should be written. — If any team member will write tests with his own ideal vision it will be a mess. Some patterns, applicable to unit tests on Java or Python, do not fit for integration tests on JavaScript and vice versa. …

The main tools for writing UI tests are: browser, IDE and testing framework documentation. — Playwright’s documentation is rich and intricate at the same time. Sometimes you can make a check or perform an action one way, and after a while find that it could be done in another way — just because you look into the API section instead of Docs or vice versa. …

Testing JSON could be a part of contract testing — you check whether the response body corresponds to specification (or contract or terms of reference). — The most appropriate way to do that is through JSON Schema — the method of description of the structure of the JSON data. Besides JSON Schema, each individual key/value pair can be checked for compliance with a number of criteria from the specification.

Sometimes, as a test engineer, you have to deal with advanced technology, such as WebSockets position itself. — If you have ever tested HTTP API, then you will not encounter very difficulties with testing bidirectional messages. But there are a few features inherent in WebSockets which should be taken into account before starting testing. Theory A WebSocket is a persistent connection between client and server. WebSockets provide a full-duplex…

As a test engineer I have been using WebdriverIO with Selenium WebDriver for frontend automation for a few years. — Recently I got an opportunity to move away from Selenium and therefore had to compare alternatives (inside my usual stack of TypeScript and Node.js): Cypress, as the most hyped automation tool; Playwright, as a more high-level tool close to the browser. Puppeteer did not hit my shortlist because it is…

As a web application test engineer, you need to test backend (APIs) as easy as frontend (UI in a browser). — Dozens of articles appear every year that tell about «the best tools for API testing» including Swagger (which is a tool for documentation and should be implemented by developers), REST Assured (which is a DSL for Java projects and requires programming skills), JMeter (which is a tool for load testing)…

The DevTools «Network» tab provides almost everything for API testing — from checking responses to making requests. — As a web application test engineer, you need to test integration of backend (APIs) with frontend (UI in a browser). During this activity the DevTools «Network» tab should be opened as a «must have» tool, because of the features described below: Network Activity Request Details Advanced Filters