GraphQL
GraphQL APIs require a layered testing strategy that covers resolvers in isolation, schema stitching, and full client-to-server flows. This guide walks through unit testing individual resolvers with Jest, integration testing with Apollo Server's executeOperation, end-to-end testing with real clients, mocking with MSW, and testing subscriptions — with tool recommendations
Expo
Expo adds a layer of abstraction over React Native that requires specific testing strategies. The jest-expo preset handles most of the configuration complexity, but mocking expo-* modules, testing Expo Router's file-based navigation, and connecting Detox to the bare workflow each have their own patterns. This guide covers unit
Apollo Server
Apollo Server v4 introduced a cleaner testing API centered on executeOperation, which lets you run full GraphQL operations without spinning up an HTTP server. This post covers testing resolvers, DataSources, authentication via context, subscriptions with graphql-ws, and how to use snapshot testing effectively for GraphQL responses — all with Jest. Key
React Native
@testing-library/react-native brings the same user-centric testing philosophy to mobile that Testing Library brought to the web. This guide covers component rendering, custom hook testing with renderHook, mocking stubborn native modules, taming async state with waitFor and findBy, and the act() gotchas that trip up even experienced React Native developers.
Testing
Socket.io applications require testing at three layers: the HTTP upgrade handshake, the event protocol layer (emit/on, ACKs, rooms), and real concurrency behavior under load. This guide covers in-process test setup, Jest event testing, middleware mocking, and scalable load patterns. Socket.io is the de-facto standard for bidirectional real-time
Testing
WebSocket testing is one of those areas where developers often wing it — manually opening a browser console, firing a few messages, and calling it done. That works until it doesn't: a race condition in reconnection logic, a dropped message during high load, or a broken event sequence that
Testing
Jest snapshot testing is simultaneously the most misused testing feature in the React ecosystem and genuinely useful when applied correctly. Teams either avoid it entirely (too fragile) or over-use it (snapshot everything and update blindly). Neither is right. This guide covers how snapshot testing actually works, when it provides real