prove-it-tdd

prove-it-tdd is a cursor rule for Cursor from MeenakshiSundaram-MS/prove-it. It costs 28 tokens per session (557 once invoked), scanned A, original, MIT.

A test-first development rule, often called TDD, where a failing test is written before the implementation and then made to pass.

In plain words
What is it for?
Use it when adding or changing behavior in projects using test tools such as Jest, Pytest, Go test, or Cargo test.
Why use it?
It shows that the test detects the missing or incorrect behavior, and records the change from failure to success.

Cursor rule for Cursor

Written for Cursor: installed under .cursor/.

Good fit Use it when adding or changing behavior in projects using test tools such as Jest, Pytest, Go test, or Cargo test.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/meenakshisundaram-ms/prove-it/prove-it-tdd
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.

Clone the repo
git clone --depth 1 https://github.com/MeenakshiSundaram-MS/prove-it

Made for: Cursor.

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 prove-it-tdd

README.md
[![agentmods](https://agentmods.dev/badge/rules/meenakshisundaram-ms/prove-it/prove-it-tdd/github.svg)](https://agentmods.dev/rules/meenakshisundaram-ms/prove-it/prove-it-tdd)
Your own site
<a href="https://agentmods.dev/rules/meenakshisundaram-ms/prove-it/prove-it-tdd"><img src="https://agentmods.dev/badge/rules/meenakshisundaram-ms/prove-it/prove-it-tdd/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for prove-it-tdd

Your own site · 80×15
<a href="https://agentmods.dev/rules/meenakshisundaram-ms/prove-it/prove-it-tdd"><img src="https://agentmods.dev/badge/rules/meenakshisundaram-ms/prove-it/prove-it-tdd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 28 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 557 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 $0.00028 $0.00557
Opus 5 $0.00014 $0.00279
Sonnet 5 $0.00006 $0.00111
Haiku 4.5 $0.00003 $0.00056

Measured 11d ago against content hash 26b5fb8fc5ff, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

prove-it-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 11d 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.

.cursor/rules/prove-it-tdd.mdc · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

prove-it — TDD Mode

Write the failing test first. Show it fails. Then implement. Show it passes.

Mandatory Sequence

1 — Verification Plan

VERIFICATION PLAN
─────────────────
Test name:    [what the test asserts]
Framework:    [jest / pytest / go test / cargo test / etc.]
Failing for:  [why it will fail — function doesn't exist / wrong return / missing branch]

2 — Write the Failing Test

Write ONLY the test. No implementation yet. A test that passes without any implementation is a bad test — fix it before proceeding.

3 — Show Red

RED — expected failure
──────────────────────
Command: [test command]
Output:
  [paste actual failure output — the real error, not a summary]

4 — Implement

Write the minimum code to make the test pass. No gold-plating beyond what the test requires.

5 — Show Green

GREEN — passing
───────────────
Command: [same test command as RED]
Output:
  [paste actual passing output]

6 — Refactor (if any)

If you refactor: re-run and show output again. A refactor that breaks tests is not a refactor — revert it.

7 — Say Done

Only after the GREEN block is shown.

Red→Green Integrity Rule

The test name in RED and the test name in GREEN must be the same.

Showing red on test A then green on test B is a violation — the test for the actual implementation was never proven to be failing first.

If you notice this: go back, show the correct test failing, then show it passing.

When a Test Passes on First Run Without Implementation

This means the test is not testing the right thing. Debug:

  • Is the assertion actually checking the new behavior?
  • Is there a pre-existing implementation that already satisfies the test?
  • Is the import path correct?

Fix the test before writing implementation.

Refactoring Phase Rules

  • Refactor means: restructure without changing behavior
  • Every refactor must be followed by a passing test run
  • Show the test output after each refactor step
  • If a refactor introduces a failure: revert it and try a smaller change

Read the full file on GitHub · 85 lines

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. 11d ago First seen · 85 lines · 28 tokens per session scan A 26b5fb8fc5ff

Subscribe to this mod's changes

prove-it-tdd is a cursor rule published in the GitHub repository MeenakshiSundaram-MS/prove-it (2 stars, last pushed 4mo ago), licensed MIT. It adds 28 tokens to every session and 557 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.