A test-driven development (TDD) guide for writing tests before or alongside code. TDD uses a repeating cycle of writing a failing test, making it pass, and improving the code.

Use it to generate tests for JavaScript, TypeScript, Python, and Java, analyze LCOV, JSON, or XML coverage reports, create test data and mocks, and review test quality.

It helps turn requirements into organized tests, reveal untested cases, and keep tests readable and independent.

tdd-guide — Skill for Claude Code by yezannnnn

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.

Any agent

npx skills add yezannnnn/agentGroup --skill tdd-guide

Clone the repo

git clone --depth 1 https://github.com/yezannnnn/agentGroup

Made for: Claude Code.

Or install engineering-skills, the plugin that ships this one along with the rest of its 17 skills.

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/skills/yezannnnn/agentgroup/tdd-guide.svg)](https://agentmods.dev/skills/yezannnnn/agentgroup/tdd-guide)

Your own site

<a href="https://agentmods.dev/skills/yezannnnn/agentgroup/tdd-guide"><img src="https://agentmods.dev/badge/skills/yezannnnn/agentgroup/tdd-guide.svg" alt="Measured on agentmods" height="20"></a>

Per session 19 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,015 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.

Model	Per session	Once invoked
Fable 5.1	$0.00019	$0.01015
Opus 5	$0.00010	$0.00508
Sonnet 5	$0.00004	$0.00203
Haiku 4.5	$0.00002	$0.00102

Measured 8d ago against content hash 313ee021abe3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, 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.

The scan reads SKILL.md. This mod also ships 8 executable files (scripts/coverage_analyzer.py, scripts/fixture_generator.py, scripts/format_detector.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

jarvis/skills/engineering-team/tdd-guide/SKILL.md · 119 lines

How it starts

The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.

TDD Guide

Test-driven development skill for generating tests, analyzing coverage, and guiding red-green-refactor workflows across Jest, Pytest, JUnit, and Vitest.

Capabilities
Workflows
Tools
Input Requirements
Limitations

Capabilities

Capability	Description
Test Generation	Convert requirements or code into test cases with proper structure
Coverage Analysis	Parse LCOV/JSON/XML reports, identify gaps, prioritize fixes
TDD Workflow	Guide red-green-refactor cycles with validation
Framework Adapters	Generate tests for Jest, Pytest, JUnit, Vitest, Mocha
Quality Scoring	Assess test isolation, assertions, naming, detect test smells
Fixture Generation	Create realistic test data, mocks, and factories

Workflows

Generate Tests from Code

Provide source code (TypeScript, JavaScript, Python, Java)
Specify target framework (Jest, Pytest, JUnit, Vitest)
Run test_generator.py with requirements
Review generated test stubs
Validation: Tests compile and cover happy path, error cases, edge cases

Analyze Coverage Gaps

Generate coverage report from test runner (npm test -- --coverage)
Run coverage_analyzer.py on LCOV/JSON/XML report
Review prioritized gaps (P0/P1/P2)
Generate missing tests for uncovered paths
Validation: Coverage meets target threshold (typically 80%+)

TDD New Feature

Write failing test first (RED)
Run tdd_workflow.py --phase red to validate
Implement minimal code to pass (GREEN)
Run tdd_workflow.py --phase green to validate
Refactor while keeping tests green (REFACTOR)
Validation: All tests pass after each cycle

Tools

Tool	Purpose	Usage
`test_generator.py`	Generate test cases from code/requirements	`python scripts/test_generator.py --input source.py --framework pytest`
`coverage_analyzer.py`	Parse and analyze coverage reports	`python scripts/coverage_analyzer.py --report lcov.info --threshold 80`
`tdd_workflow.py`	Guide red-green-refactor cycles	`python scripts/tdd_workflow.py --phase red --test test_auth.py`
`framework_adapter.py`	Convert tests between frameworks	`python scripts/framework_adapter.py --from jest --to pytest`
`fixture_generator.py`	Generate test data and mocks	`python scripts/fixture_generator.py --entity User --count 5`
`metrics_calculator.py`	Calculate test quality metrics	`python scripts/metrics_calculator.py --tests tests/`
`format_detector.py`	Detect language and framework	`python scripts/format_detector.py --file source.ts`
`output_formatter.py`	Format output for CLI/desktop/CI	`python scripts/output_formatter.py --format markdown`

Read the full file on GitHub · 119 lines

Files

What ships with it

17 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

8d ago First seen · 119 lines · 19 tokens per session scan A 313ee021abe3

Subscribe to this mod's changes

tdd-guide is a skill published in the GitHub repository yezannnnn/agentGroup (149 stars, last pushed 3mo ago), licensed MIT. It adds 19 tokens to every session and 1,015 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 2026-08-30.

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