tdd-workflow

tdd-workflow is a skill for Claude Code from mathiasbourgoin/roster. It costs 22 tokens per session (833 once invoked), scanned A, original, MIT.

A test-driven development workflow that guides coding through three steps: write a failing test, make it pass with the smallest change, then improve the code and check coverage.

In plain words
What is it for?
Use it when adding a feature or fixing a bug in projects using frameworks such as Vitest, Jest, pytest, Cargo, Go, or ExUnit.
Why use it?
It helps catch incorrect assumptions early and keeps each code change checked by an automated test.

Skill for Claude Code

Written for Claude Code: when-to-use in frontmatter. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it when adding a feature or fixing a bug in projects using frameworks such as Vitest, Jest, pytest, Cargo, Go, or ExUnit.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mathiasbourgoin/roster/tdd-workflow
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add mathiasbourgoin/roster --skill tdd-workflow
Clone the repo
git clone --depth 1 https://github.com/mathiasbourgoin/roster

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for tdd-workflow

README.md
[![agentmods](https://agentmods.dev/badge/skills/mathiasbourgoin/roster/tdd-workflow.svg)](https://agentmods.dev/skills/mathiasbourgoin/roster/tdd-workflow)
Your own site
<a href="https://agentmods.dev/skills/mathiasbourgoin/roster/tdd-workflow"><img src="https://agentmods.dev/badge/skills/mathiasbourgoin/roster/tdd-workflow.svg" alt="Measured on agentmods" height="20"></a>
Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 833 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00022 $0.00833
Opus 5 $0.00011 $0.00417
Sonnet 5 $0.00004 $0.00167
Haiku 4.5 $0.00002 $0.00083

Measured 7d ago against content hash a3ff48c3f49c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

tdd-workflow scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/tdd-workflow/SKILL.md · 91 lines

How it starts

The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.

TDD Workflow

You guide the user through a strict red-green-refactor cycle for the feature or fix described in $ARGUMENTS.

Language Detection

Before starting, detect the project's test framework:

Marker Runner Command
package.json with vitest Vitest npx vitest run
package.json with jest Jest npx jest
pytest.ini / pyproject.toml / conftest.py pytest pytest
Cargo.toml cargo test cargo test
dune-project dune test dune runtest
go.mod go test go test ./...
mix.exs ExUnit mix test
*.cabal / stack.yaml HSpec/Tasty cabal test or stack test

If no marker found, ask the user which framework to use.

Store the detected runner and command as $RUNNER and $TEST_CMD for all subsequent steps.

Steps

1. RED — Write Failing Test

  • Parse $ARGUMENTS to understand the desired behavior.
  • Write a test that asserts the expected behavior. The test must compile/parse but fail when run.
  • Run $TEST_CMD. Confirm the new test fails. If it passes, STOP — the behavior already exists or the test is wrong. Ask the user to clarify.

2. GREEN — Minimal Implementation

  • Write the minimum code to make the failing test pass. No extra features, no premature abstractions.
  • Run $TEST_CMD. Confirm the new test passes AND all existing tests still pass.
  • If any test fails, fix only the implementation (never the test).

3. REFACTOR — Improve

  • Review both the test and implementation for:
    • Duplication (DRY)
    • Naming clarity
    • Unnecessary complexity
    • Extract helpers if test setup is repeated
  • Apply improvements. Run $TEST_CMD to confirm everything stays green.

4. VERIFY — Coverage Check

  • Run coverage if the framework supports it:
    • Jest/Vitest: $TEST_CMD --coverage
    • pytest: pytest --cov
    • cargo: cargo tarpaulin (if installed) or cargo llvm-cov
    • go: go test -cover ./...
  • Report coverage. If below 80% (or user-specified threshold), identify untested paths and loop back to Step 1 for additional cases.

Read the full file on GitHub · 91 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 91 lines · 22 tokens per session scan A a3ff48c3f49c

Subscribe to this mod's changes

tdd-workflow is a skill published in the GitHub repository mathiasbourgoin/roster (2 stars, last pushed yesterday), licensed MIT. It adds 22 tokens to every session and 833 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.