tdd-guide

tdd-guide is an agent for Claude Code from YousefNabil-SOC/claude-apex. It costs 42 tokens per session (699 once invoked), scanned A, a copy of tdd-guide, MIT.

A coding assistant focused on Test-Driven Development (TDD), a method where you write a failing test before writing the code that should pass it. It follows the cycle of writing a test, making it pass, and improving the code.

In plain words
What is it for?
Use it for new features, bug fixes, and refactoring, with unit tests for individual functions, integration tests for connected parts, and end-to-end tests for important user flows.
Why use it?
It reduces the chance of breaking existing behavior and exposes edge cases while a feature or fix is being built. It also checks test coverage, which measures how much of the code tests exercise.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Good fit Use it for new features, bug fixes, and refactoring, with unit tests for individual functions, integration tests for connected parts, and end-to-end tests for important user flows.

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Install with agentmods
npx agentmods add agents/yousefnabil-soc/claude-apex/tdd-guide
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/YousefNabil-SOC/claude-apex

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-guide

README.md
[![agentmods](https://agentmods.dev/badge/agents/yousefnabil-soc/claude-apex/tdd-guide/github.svg)](https://agentmods.dev/agents/yousefnabil-soc/claude-apex/tdd-guide)
Your own site
<a href="https://agentmods.dev/agents/yousefnabil-soc/claude-apex/tdd-guide"><img src="https://agentmods.dev/badge/agents/yousefnabil-soc/claude-apex/tdd-guide/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 tdd-guide

Your own site · 80×15
<a href="https://agentmods.dev/agents/yousefnabil-soc/claude-apex/tdd-guide"><img src="https://agentmods.dev/badge/agents/yousefnabil-soc/claude-apex/tdd-guide.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 42 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 699 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 95% copy Near-identical to another mod 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 $0.00042 $0.00699
Opus 5 $0.00021 $0.00349
Sonnet 5 $0.00008 $0.00140
Haiku 4.5 $0.00004 $0.00070

Measured 8d ago against content hash de339a6158d7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

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 8d 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.

Origin

This is a copy

95% identical to tdd-guide — 6 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.

agents/tdd-guide.md · 92 lines

How it starts

The opening of the file, as written. The whole thing — 92 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

  1. Null/Undefined input
  2. Empty arrays/strings
  3. Invalid types passed
  4. Boundary values (min/max)
  5. Error paths (network failures, DB errors)
  6. Race conditions (concurrent operations)
  7. Large data (performance with 10k+ items)
  8. 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%+

Read the full file on GitHub · 92 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. 8d ago First seen · 92 lines · 42 tokens per session scan A de339a6158d7

Subscribe to this mod's changes

tdd-guide is an agent published in the GitHub repository YousefNabil-SOC/claude-apex (2 stars, last pushed 2mo ago), licensed MIT. It adds 42 tokens to every session and 699 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to tdd-guide, differing in 6 lines, and is treated as a copy.