A test-driven development command. TDD means writing a failing test first, adding the smallest code that passes it, and then improving the code while keeping the tests passing.

Use it to develop features with tests for normal cases, edge cases, and errors, while checking that ordinary code reaches at least 80% test coverage.

It catches mistakes early and makes the expected behavior explicit before the implementation is built.

tdd — Command for coding agents by marshall0524: A test-driven development command.

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 commands/marshall0524/everythingclaudecode/tdd

Clone the repo

git clone --depth 1 https://github.com/marshall0524/everythingclaudecode

Or install everything-claude-code, the plugin that ships this one along with the rest of its 17 skills, 31 commands, 8 agents.

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.

README.md

[![agentmods](https://agentmods.dev/badge/commands/marshall0524/everythingclaudecode/tdd.svg)](https://agentmods.dev/commands/marshall0524/everythingclaudecode/tdd)

Your own site

<a href="https://agentmods.dev/commands/marshall0524/everythingclaudecode/tdd"><img src="https://agentmods.dev/badge/commands/marshall0524/everythingclaudecode/tdd.svg" alt="Measured on agentmods" height="20"></a>

Per session 11 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 422 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin 100% 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.

Model	Per session	Once invoked
Fable 5	$0.00011	$0.00422
Opus 5	$0.00005	$0.00211
Sonnet 5	$0.00002	$0.00084
Haiku 4.5	$0.00001	$0.00042

Measured 3d ago against content hash 0f57c5163f08, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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 3d 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

100% identical to tdd — 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.

.opencode/commands/tdd.md · 67 lines

What it actually says

TDD Command

Implement the following using strict test-driven development: $ARGUMENTS

TDD Cycle (MANDATORY)

RED → GREEN → REFACTOR → REPEAT

RED: Write a failing test FIRST
GREEN: Write minimal code to pass the test
REFACTOR: Improve code while keeping tests green
REPEAT: Continue until feature complete

Your Task

Step 1: Define Interfaces (SCAFFOLD)

Define TypeScript interfaces for inputs/outputs
Create function signature with throw new Error('Not implemented')

Step 2: Write Failing Tests (RED)

Write tests that exercise the interface
Include happy path, edge cases, and error conditions
Run tests - verify they FAIL

Step 3: Implement Minimal Code (GREEN)

Write just enough code to make tests pass
No premature optimization
Run tests - verify they PASS

Step 4: Refactor (IMPROVE)

Extract constants, improve naming
Remove duplication
Run tests - verify they still PASS

Step 5: Check Coverage

Target: 80% minimum
100% for critical business logic
Add more tests if needed

Coverage Requirements

Code Type	Minimum
Standard code	80%
Financial calculations	100%
Authentication logic	100%
Security-critical code	100%

Test Types to Include

Unit Tests: Individual functions
Edge Cases: Empty, null, max values, boundaries
Error Conditions: Invalid inputs, network failures
Integration Tests: API endpoints, database operations

MANDATORY: Tests must be written BEFORE implementation. Never skip the RED phase.

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.

3d ago First seen · 67 lines · 11 tokens per session scan A 0f57c5163f08

Subscribe to this mod's changes

tdd is a command published in the GitHub repository marshall0524/everythingclaudecode (35 stars, last pushed 1mo ago), licensed MIT. It adds 11 tokens to every session and 422 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to tdd, differing in 0 lines, and is treated as a copy.

TDD Testing

tdd