# Writing tests

> Use when deciding whether to add tests or changing mocks, snapshots or assertions.

Writes and maintains meaningful tests with minimal machinery. Use when deciding whether to add tests, investigating failures, or changing assertions, snapshots, fixtures, mocks, skips, or tolerances.

## Facts

- Type: Agent skill
- Discipline: Engineering
- Author: Lachlan Donald (https://github.com/lox)
- Upstream: https://github.com/lox/agent-skills/blob/main/writing-tests/SKILL.md
- Source file: https://raw.githubusercontent.com/lox/agent-skills/main/writing-tests/SKILL.md (2406 bytes, sha256:65f035a95d9509ac92b00439a4345a3d844a2e342f53f144a449111f87d25c9d)
- Licence: none declared by the repo
- Upstream copy last changed: 2026-09-17
- Status: listed, not yet ruled on by the curator

## Use it

I want to use the Writing tests skill by Lachlan Donald.
This is what it does, in the author's own words: Writes and maintains meaningful tests with minimal machinery. Use when deciding whether to add tests, investigating failures, or changing assertions, snapshots, fixtures, mocks, skips, or tolerances.
Download the whole folder at https://github.com/lox/agent-skills/tree/main/writing-tests, SKILL.md and every file beside it, into your skills directory: ~/.claude/skills/writing-tests/ for Claude Code, ~/.agents/skills/writing-tests/ for Codex, ~/.cursor/skills/writing-tests/ for Cursor. Get it from the author's repo, not from startupskills.dev.
Then tell me the path you installed it to and how to invoke it.

Nothing here is vendored: install from the author's repo. This file carries none of the author's file.

## Links

- Page: https://startupskills.dev/lox/writing-tests
- Author: https://startupskills.dev/lox
- Index: https://startupskills.dev/llms.txt

## The file

Not reproduced here: the repo does not license republication. Read it on the author's GitHub:
https://github.com/lox/agent-skills/blob/main/writing-tests/SKILL.md