Testing
SendGrid powers email delivery for many production applications. Testing SendGrid integration involves mocking the API client for unit tests, using SendGrid's sandbox mode for integration tests, and testing Event Webhooks for delivery tracking. This guide covers all three layers with Node.js examples. Key Takeaways Enable sandbox mode
Testing
Nodemailer is the most popular Node.js email library. Testing Nodemailer flows has two approaches: mock the transporter entirely (unit tests) or use Ethereal's fake SMTP server (integration tests). This guide covers both approaches, with Jest examples for testing email content, attachments, and error handling without sending real
Testing
React Native's cross-platform model means accessibility bugs can appear on iOS, Android, or both, often in different forms. A layered testing approach — jest-native for component tests, react-native-axe-core for runtime audits, and Detox for end-to-end screen reader behavior — catches issues at every level of the stack. React Native gives
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
WebRTC applications are notoriously hard to test because they involve browser APIs, network negotiation, and real-time media. This guide covers mocking RTCPeerConnection in Jest, intercepting WebRTC in Playwright, measuring media quality with getStats(), and simulating adverse network conditions. WebRTC powers video calls, screen sharing, and peer-to-peer data channels — but its
Testing
axe-core is the most widely deployed accessibility rules engine in the world, and it works inside Appium test suites — not just on the web. By injecting axe-core into WebView contexts within hybrid and cross-platform apps, you can run the same accessibility rules in your mobile CI pipeline that your web
Testing
Server-Sent Events are simple to use but tricky to test because streaming responses, reconnection logic, and event routing all behave differently from normal HTTP. This guide covers pytest with httpx, Playwright EventSource interception, and k6 load testing for SSE endpoints. Server-Sent Events (SSE) provide a lightweight, one-directional stream from server
Testing
WebXR applications are notoriously hard to test because they require browser APIs that only activate with real hardware. This guide shows how to use Playwright's WebXR emulation to test immersive sessions, controller input, hit testing, and XRSession lifecycle — all in CI without a headset. WebXR brings immersive experiences
Testing
Puppeteer's page.pdf() generates PDFs from HTML pages — but verifying the output requires more than file existence checks. This guide covers testing PDF content via text extraction, visual regression diffs, layout assertions, and metadata checks using Node.js, Puppeteer, and the pdf-parse library. Key Takeaways Use pdf-parse to
Testing
Every headless CMS has different testing requirements. Contentful and Sanity are managed cloud services — you test your integration code against mock clients or their preview/test APIs. Strapi and Directus are self-hosted — you test against a real running instance. This guide maps out the testing layers for each, with tooling
Testing
Strapi v5 exposes content via REST and GraphQL APIs. Testing these APIs involves three layers: unit tests for custom service logic, integration tests against a running Strapi instance with a test database, and permission tests that verify role-based access. This guide covers all three using Jest and Supertest. Key Takeaways
Testing
Contentful doesn't have a built-in testing framework, but its Delivery API client, content model structure, and rich text renderer are all testable in Jest. This guide covers mocking the Contentful SDK, testing content model shape assumptions, validating rich text output, and writing integration tests against the Preview API.