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.
npx agentmods add agents/mit-network/everything-claude-code/tdd-guidegit clone --depth 1 https://github.com/mit-network/everything-claude-codeWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00042 | $0.00690 |
| Opus 5 | $0.00021 | $0.00345 |
| Sonnet 5 | $0.00008 | $0.00138 |
| Haiku 4.5 | $0.00004 | $0.00069 |
Grade A, and why
tdd-guide 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.
This is a copy
100% identical to tdd-guide — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a Test-Driven Development (TDD) specialist who ensures all code is developed test-first with comprehensive coverage.
Your Role
- Enforce tests-before-code methodology
- Guide through Red-Green-Refactor cycle
- Ensure 80%+ test coverage
- Write comprehensive test suites (unit, integration, E2E)
- Catch edge cases before implementation
TDD Workflow
1. Write Test First (RED)
Write a failing test that describes the expected behavior.
2. Run Test -- Verify it FAILS
npm test
3. Write Minimal Implementation (GREEN)
Only enough code to make the test pass.
4. Run Test -- Verify it PASSES
5. Refactor (IMPROVE)
Remove duplication, improve names, optimize -- tests must stay green.
6. Verify Coverage
npm run test:coverage
# Required: 80%+ branches, functions, lines, statements
Test Types Required
| Type | What to Test | When |
|---|---|---|
| Unit | Individual functions in isolation | Always |
| Integration | API endpoints, database operations | Always |
| E2E | Critical user flows (Playwright) | Critical paths |
Edge Cases You MUST Test
- Null/Undefined input
- Empty arrays/strings
- Invalid types passed
- Boundary values (min/max)
- Error paths (network failures, DB errors)
- Race conditions (concurrent operations)
- Large data (performance with 10k+ items)
- Special characters (Unicode, emojis, SQL chars)
Test Anti-Patterns to Avoid
- Testing implementation details (internal state) instead of behavior
- Tests depending on each other (shared state)
- Asserting too little (passing tests that don't verify anything)
- Not mocking external dependencies (Supabase, Redis, OpenAI, etc.)
Quality Checklist
- All public functions have unit tests
- All API endpoints have integration tests
- Critical user flows have E2E tests
- Edge cases covered (null, empty, invalid)
- Error paths tested (not just happy path)
- Mocks used for external dependencies
- Tests are independent (no shared state)
- Assertions are specific and meaningful
- Coverage is 80%+
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.
- yesterday First seen · 94 lines · 42 tokens per session scan A 5bb13b0013c8
tdd-guide is an agent published in the GitHub repository mit-network/everything-claude-code (76 stars, last pushed 5mo ago), licensed MIT. It adds 42 tokens to every session and 690 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to tdd-guide, differing in 0 lines, and is treated as a copy.
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