dev-tdd

A coding agent that follows test-driven development, or TDD: write a failing test, add the smallest code that passes it, then improve the code.

In plain words
What is it for?
Use it to build features, add tests to existing code, set up testing and coverage tools, and configure continuous integration. It also requires edge-case tests and separate test, feature, and refactoring commits.
Why use it?
It helps catch regressions and makes the expected behavior explicit before implementation is written.

Agent for Claude Code

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.

agentmods
npx agentmods add agents/christopherlouet/claude-base/dev-tdd
Clone the repo
git clone --depth 1 https://github.com/christopherlouet/claude-base

Made for: Claude Code.

Per session 118 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 383 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00118 $0.00383
Opus 5 $0.00059 $0.00192
Sonnet 5 $0.00024 $0.00077
Haiku 4.5 $0.00012 $0.00038

Measured 2d ago against content hash 9672dd6f6a20, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dev-tdd 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 2d 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.

.claude/agents/dev-tdd.md · 40 lines

What it actually says

Agent DEV-TDD

Test-driven development. The dev-tdd skill provides the detailed methodology.

Cycle

RED (failing test) → GREEN (minimal code) → REFACTOR (clean up) → repeat

Strict rules

  • NEVER write the code before the tests
  • YOU MUST cover edge cases (null, undefined, empty, boundaries)
  • NEVER use mocks except for external deps (API, DB, filesystem)
  • NEVER modify a test to make it pass — fix the implementation
  • A test that passes from the start is a BAD test

Output

  1. Tests first: Complete test file
  2. Implementation: Minimal code that makes the tests pass
  3. Refactoring: Clean code
  4. Separate commits: test(scope)feat(scope)refactor(scope)
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. 2d ago First seen · 40 lines · 118 tokens per session scan A 9672dd6f6a20

Subscribe to this mod's changes

dev-tdd is an agent published in the GitHub repository christopherlouet/claude-base (5 stars, last pushed 2d ago), licensed MIT. It adds 118 tokens to every session and 383 once invoked, about $0.0006 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.

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