test-driven-development

test-driven-development is a skill for Claude Code, Codex from tolgakisaogullari/SumelaOS. It costs 23 tokens per session (498 once invoked), scanned A, original, MIT.

A test-first workflow for building features and fixing bugs. TDD means writing a test that fails, adding the smallest code to pass it, then cleaning up the code.

In plain words
What is it for?
Use it before implementing a feature or bug fix when the user has chosen TDD. It covers new behavior, bug reproductions, security constraints, and edge cases.
Why use it?
It checks that the test really exposes the missing behavior and helps prevent existing tests from breaking. It also discourages adding code the change does not need.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it before implementing a feature or bug fix when the user has chosen TDD. It covers new behavior, bug reproductions, security constraints, and edge cases.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tolgakisaogullari/sumelaos/test-driven-development
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 tolgakisaogullari/SumelaOS --skill test-driven-development
Clone the repo
git clone --depth 1 https://github.com/tolgakisaogullari/SumelaOS

Made for: Claude Code, Codex.

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 test-driven-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/tolgakisaogullari/sumelaos/test-driven-development/github.svg)](https://agentmods.dev/skills/tolgakisaogullari/sumelaos/test-driven-development)
Your own site
<a href="https://agentmods.dev/skills/tolgakisaogullari/sumelaos/test-driven-development"><img src="https://agentmods.dev/badge/skills/tolgakisaogullari/sumelaos/test-driven-development/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 test-driven-development

Your own site · 80×15
<a href="https://agentmods.dev/skills/tolgakisaogullari/sumelaos/test-driven-development"><img src="https://agentmods.dev/badge/skills/tolgakisaogullari/sumelaos/test-driven-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 498 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 $0.00023 $0.00498
Opus 5 $0.00012 $0.00249
Sonnet 5 $0.00005 $0.00100
Haiku 4.5 $0.00002 $0.00050

Measured 9d ago against content hash 8fd5d814ce30, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

test-driven-development 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 9d 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.

.sumela/skills/test-driven-development/SKILL.md · 28 lines

What it actually says

<tdd_workflow> If the user approved TDD, execute this cycle strictly in order for EVERY behavior change or bugfix:

  1. RED (Write Failing Test): Write a single, minimal test demonstrating the desired behavior or reproducing the bug. Test actual behavior, not mock behavior. Where applicable, include tests for security constraints and edge cases based on the secure-coding-standard.
  2. VERIFY RED (Watch It Fail): Run the test. You MUST verify that it fails specifically because the feature is missing or the bug exists (not due to syntax or setup errors).
  3. GREEN (Minimal Code): Write the absolute minimum implementation code required to make the test pass. Actively apply secure-coding-standard principles while writing this code. Do not over-engineer or add unrequested features (YAGNI).
  4. VERIFY GREEN (Watch It Pass): Run the test suite. Ensure the new test passes and no existing tests are broken.
  5. REFACTOR (Clean Up): Only after the test is green, refactor the code to remove duplication and improve names. Tests must remain green. </tdd_workflow>

<testing_constraints>

  • CONDITIONAL RATIONALIZATION: If the user opted INTO TDD, do not skip it for "simple" changes, emergencies, or refactoring. Strict compliance is required.
  • AVOID MOCKS: Test real logic whenever possible.
  • NO TEST POLLUTION: Never add test-only methods or variables to production code.
  • SECURITY COVERAGE: Ensure authentication, input validation, and boundary limits are tested if writing tests for secure features.
  • REFERENCE: Consult ./testing-anti-patterns.md before adding mocks or complex test utilities. </testing_constraints>
Files

What ships with it

1 file 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.

  1. 9d ago First seen · 28 lines · 23 tokens per session scan A 8fd5d814ce30

Subscribe to this mod's changes

test-driven-development is a skill published in the GitHub repository tolgakisaogullari/SumelaOS (4 stars, last pushed 14d ago), licensed MIT. It adds 23 tokens to every session and 498 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.