testing – Page 7 – Türker Yıldırım

An API versioned for the first time in six years

Deep diveMarch 6, 202514 min read

Six years of additive-only changes, and a change that cannot be additive. A field whose meaning must change, with four consumers reading it.

Tailwind 4, and the stylesheet we had already written

Deep diveFebruary 13, 20259 min read

4.0 in January, a CSS-first configuration, and a genuine reason to look again at a decision that had been made three times.

The snapshot I approved without reading

NoteFebruary 3, 20252 min read

A snapshot test that failed, an approval taken on the basis that the change was intentional, and a diff nobody opened. A snapshot test moves the verification from…

Mutation testing on a second directory

NoteJanuary 23, 20252 min read

A technique applied to one directory in 2023, extended to a second, with a much worse result and a better reason. A low score on code that implements…

The generated specification that drifted from the second version

NoteJanuary 17, 20251 min read

A specification generated from the router, which is drift-proof until there are two routers describing two versions. Generating from the router guarantees that a documented endpoint exists and…

Property hooks, and the getter that was a habit

Deep diveDecember 16, 202410 min read

8.4 on 21 November, and a property can have a getter without being a method. 412 getters that return a property unchanged.

A behavioural diff before and after a mechanical refactor

NoteOctober 24, 20242 min read

A refactor too large to review, and a test that compares behaviour rather than code. A corpus of four thousand real inputs, captured from a week of production…

A flush-the-cache test that found data with no home

NoteSeptember 4, 20242 min read

An integration test that clears the cache mid-scenario and asserts the application still behaves. The failure is the point: a preference written to the cache and nowhere else…

A cache that was a second database

Deep diveMay 22, 202410 min read

A cache holding data that existed nowhere else, discovered during a restart. A flush that lost four hours of user preferences.

An API that had two clients and three shapes

Deep diveMay 16, 202410 min read

One endpoint, two consumers, and a response that differs by header. Three serialisation paths for one resource, two of them accidental.