tdd: a Claude Code skill by Matt Pocock
For developers who want Claude to build features test first, one failing test at a time. Skip it if you want a whole test suite written in one go.
- Score
- 87of 100
- Rank
- #18of 239
- Installs
- 1.2Mon skills.sh
- Security
- Clear 5 scanners
- Updated
- 2026
- Context
- ~38tokens always
Install
npx skills add https://github.com/mattpocock/skills --skill tdd
Run it in your terminal. View the source
Using the Claude app rather than Claude Code? You can add a skill there too. How to add it in the app
What does tdd do?
tdd is a Claude skill that sets the rules for a red to green loop: write one failing test, then only enough code to pass it, then repeat. Before any test is written, Claude must list the seams, meaning the public interfaces to test at, note what each one catches and misses, and get your agreement. It reads GLOSSARY.md if present so test names match your domain words, and it respects ADRs. It warns against tests tied to internals, tautological assertions and writing all tests before any code. Refactoring stays out of the loop and goes to a separate code-review skill. Examples live in tests.md and mocking.md.
When should you use tdd?
Use it when
- Building a new feature test first
- Fixing a bug by first writing a test that fails
- Adding integration tests at agreed public interfaces
Skip it when
- You want code written without tests
- You need many tests generated for existing code at once
What it needs and what it can touch
What it can do
- Reads and edits project files
From reading its instructions, not from running it.
Why it scores 87
Strongest on upkeep (100 of 100), weakest on trust (65).
Is tdd safe to install?
Every scanner that checked it passed it. Scanners often miss what other scanners catch, and a skill can change after a scan. Read its source before you install it.
| Scanner | Result | Date |
|---|---|---|
| Gen Agent Trust Hub | Passed | Oct 7, 2026 |
| Socket | Passed | Oct 7, 2026 |
| Snyk | Low risk | Oct 7, 2026 |
| Runlayer | Passed | Feb 26, 2026 |
| ZeroLeaks | Passed | Apr 16, 2026 |
Details
- Installs
- 1,228,170
- Repository stars
- 321,400
- Last repository change
- Tokens always loaded
- about 38
- Tokens when used
- about 859
- License
- MIT
- Data confidence
- High
Did it do the job for you?
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tdd