- React Native – Testing
What to test and with what. `jest-expo` and React Native Testing Library, mocking the native modules that do not exist in Node, querying by accessibility label so the tests check what a screen reader would find, and the trap in the current version — `render` and `fireEvent` are async now, and forgetting an `await` produces an error that describes the opposite problem. Then where end-to-end testing takes over.
- TypeScript – The Utility Types Worth Knowing
Partial, Required, Readonly, Pick, Omit, Record, Exclude, Extract, NonNullable, ReturnType and Awaited — what each one is for, in the order you will actually need them. Including the Record in this app that turns adding a status to a union into a build error until somebody writes the label for it.
- NestJS – The Request Lifecycle
The order everything runs in, traced through one real request from the contractor API. Middleware, guards, interceptors, pipes, the handler, then interceptors and filters on the way back out — and the practical consequences of that order, which is where most of the confusing bugs in a Nest app come from.
- Spring Study Guide – REST
REST as Spring implements it. Resources, the safe and idempotent methods and why the distinction matters, status codes for each verb, @RestController versus @Controller, @RequestBody and @ResponseBody, HttpMessageConverters and how content negotiation picks one, error responses with @ControllerAdvice, and RestClient — the replacement for the RestTemplate every old answer names.
- log4j
Logging is what you have instead of a debugger when the problem happened at 3am on a server you cannot attach to. Java's logging landscape has a confusing number of libraries; the arrangement that matters is simple once you see it. The facade and the implementation There are two layers, and…