testing-ops

testing-ops is a skill for Claude Code, Codex from 0xDarkMatter/claude-mods. It costs 47 tokens per session (1,011 once invoked), scanned A, original, MIT.

A reference for testing software at different levels, from unit tests for one function to end-to-end tests for a complete user journey. It also explains TDD, a method of writing a failing test before the code that makes it pass.

In plain words
What is it for?
Use it to plan unit, integration, and end-to-end tests, choose test doubles, name tests, isolate tests, and decide where TDD fits.
Why use it?
It helps choose the right kind of test and avoid relying only on slow, expensive full-system tests.

Skill for Claude CodeCodex

Part of the claude-mods plugin — 103 skills, 3 commands, 3 agents, 4 hooks shipped together

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 skills/0xdarkmatter/claude-mods/testing-ops
Any agent
npx skills add 0xDarkMatter/claude-mods --skill testing-ops
Clone the repo
git clone --depth 1 https://github.com/0xDarkMatter/claude-mods

Made for: Claude Code, Codex.

Or install claude-mods, the plugin that ships this one along with the rest of its 103 skills, 3 commands, 3 agents, 4 hooks.

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 testing-ops

README.md
[![agentmods](https://agentmods.dev/badge/skills/0xdarkmatter/claude-mods/testing-ops.svg)](https://agentmods.dev/skills/0xdarkmatter/claude-mods/testing-ops)
Your own site
<a href="https://agentmods.dev/skills/0xdarkmatter/claude-mods/testing-ops"><img src="https://agentmods.dev/badge/skills/0xdarkmatter/claude-mods/testing-ops.svg" alt="Measured on agentmods" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,011 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00047 $0.01011
Opus 5 $0.00023 $0.00505
Sonnet 5 $0.00009 $0.00202
Haiku 4.5 $0.00005 $0.00101

Measured yesterday against content hash 4cbd4c3ddcfe, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

testing-ops 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.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/coverage-check.sh, tests/run.sh), 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.

skills/testing-ops/SKILL.md · 164 lines

How it starts

The opening of the file, as written. The whole thing — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Testing Patterns

Universal testing strategies and patterns applicable across languages.

The Test Pyramid

        /\
       /  \     E2E Tests (few, slow, expensive)
      /    \    - Full system tests
     /------\   - Real browser/API calls
    /        \
   /  Integ   \ Integration Tests (some)
  /   Tests    \ - Service boundaries
 /--------------\ - Database, APIs
/                \
/   Unit Tests    \ Unit Tests (many, fast, cheap)
------------------  - Single function/class
                    - Mocked dependencies

Test Types

Unit Tests

Scope:      Single function/method/class
Speed:      Milliseconds
Dependencies: All mocked
When:       Every code change
Coverage:   80%+ of codebase

Integration Tests

Scope:      Multiple components together
Speed:      Seconds
Dependencies: Real databases, mocked external APIs
When:       PR/merge, critical paths
Coverage:   Key integration points

End-to-End Tests

Scope:      Full user journey
Speed:      Minutes
Dependencies: Real system (or staging)
When:       Pre-deploy, nightly
Coverage:   Critical user flows only

Test Naming Convention

test_<unit>_<scenario>_<expected>

Examples:
- test_calculate_total_with_discount_returns_reduced_price
- test_user_login_with_invalid_password_returns_401
- test_order_submit_when_out_of_stock_raises_error

Arrange-Act-Assert (AAA)

def test_calculate_discount():
    # Arrange - Set up test data and dependencies
    cart = Cart()
    cart.add_item(Item(price=100))
    discount = Discount(percent=10)

    # Act - Execute the code under test
    total = cart.calculate_total(discount)

    # Assert - Verify the results
    assert total == 90

Test Doubles

Type Purpose Example
Stub Returns canned data stub.get_user.returns(fake_user)
Mock Verifies interactions mock.send_email.assert_called_once()
Spy Records calls, uses real impl spy.on(service, 'save')
Fake Working simplified impl FakeDatabase() instead of real DB
Dummy Placeholder, never used null object for required param

Read the full file on GitHub · 164 lines

Files

What ships with it

7 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.

  1. yesterday First seen · 164 lines · 47 tokens per session scan A 4cbd4c3ddcfe

Subscribe to this mod's changes

testing-ops is a skill published in the GitHub repository 0xDarkMatter/claude-mods (32 stars, last pushed 12d ago), licensed MIT. It adds 47 tokens to every session and 1,011 once invoked, about $0.0002 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 2026-09-03.