5-tdd

A test-driven development workflow for building features, fixing bugs, and refactoring. TDD means writing a failing test first, then adding the smallest code change that makes it pass.

In plain words
What is it for?
Use it to guide the cycle of writing tests, implementing code, running checks, and refactoring both production code and tests.
Why use it?
It turns the expected behaviour into a check before implementation and helps catch regressions during changes.

Cursor rule for Cursor

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 rules/cmnemoi/cursor-rules/5-tdd
Clone the repo
git clone --depth 1 https://github.com/cmnemoi/cursor-rules

Made for: Cursor.

Per session 18 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 262 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 $0.00018 $0.00262
Opus 5 $0.00009 $0.00131
Sonnet 5 $0.00004 $0.00052
Haiku 4.5 $0.00002 $0.00026

Measured yesterday against content hash 658bdb8fb259, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

5-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 yesterday.

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.

general-rules/.cursor/rules/05-workflows-and-processes/5-tdd.mdc · 21 lines

What it actually says

How to work in TDD

  1. Determine the next feature to implement
  2. Write a failing test for the feature in tests
  3. Run tests
  4. If the test fails, go to 4), else go to 1)
  5. Write the minimum amount of production code to make the test passes
  6. Run tests
  7. If the test passes, go to 7), else go to 4)
  8. Refactor production code using 1-clean-code.mdc standards
  9. Run tests
  10. If the test passes, go to 10), else go to 4)
  11. Refactor tests using 1-clean-code.mdc and 7-testing-standards.mdc standards
  12. If the test passes, go to 0), else revert and go to 10)
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. yesterday First seen · 21 lines · 18 tokens per session scan A 658bdb8fb259

Subscribe to this mod's changes

5-tdd is a cursor rule published in the GitHub repository cmnemoi/cursor-rules (2 stars, last pushed 1y ago), licensed MIT. It adds 18 tokens to every session and 262 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.