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.
npx skills add groupzer0/vs-code-agents --skill testing-patternsgit clone --depth 1 https://github.com/groupzer0/vs-code-agentsWrote 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.
[](https://agentmods.dev/skills/groupzer0/vs-code-agents/testing-patterns)<a href="https://agentmods.dev/skills/groupzer0/vs-code-agents/testing-patterns"><img src="https://agentmods.dev/badge/skills/groupzer0/vs-code-agents/testing-patterns/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.
<a href="https://agentmods.dev/skills/groupzer0/vs-code-agents/testing-patterns"><img src="https://agentmods.dev/badge/skills/groupzer0/vs-code-agents/testing-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00040 | $0.01833 |
| Opus 5.5 | $0.00016 | $0.00733 |
| Sonnet 5.5 | $0.00008 | $0.00367 |
| Haiku 4.5 | $0.00004 | $0.00183 |
Grade A, and why
testing-patterns 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 280 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Testing Patterns
Systematic approach to effective testing. Use this skill when:
- Writing or changing tests (load anti-patterns reference)
- Designing test strategies for new features
- Reviewing test coverage adequacy
- Implementing test frameworks or infrastructure
Test-Driven Development (TDD)
TDD is MANDATORY for new feature code. Write tests before implementation.
The TDD Cycle
┌─────────────────────────────────────────┐
│ │
│ 1. RED → Write failing test │
│ 2. GREEN → Minimal code to pass │
│ 3. REFACTOR → Clean up, tests stay green │
│ 4. REPEAT │
│ │
└─────────────────────────────────────────┘
Why TDD?
| Benefit | How TDD Delivers |
|---|---|
| Prevents over-mocking | You see what test needs before mocking |
| No test-only production code | Minimal implementation = no extras |
| Tests real behavior | Failing test proves it tests something real |
| Better design | Testable code = loosely coupled code |
When TDD Applies
| Situation | TDD? | Notes |
|---|---|---|
| New features | ✅ Always | Core workflow |
| Behavior changes | ✅ Always | Modify test first, then code |
| Bug fixes | ✅ Preferred | Write test reproducing bug first |
| Pure refactors | ⚠️ Optional | Existing tests should cover |
| Exploratory spikes | ❌ Skip | But TDD rewrite after |
TDD Violations
If implementation arrives without tests:
- Reject with "TDD Required"
- Specify which tests should exist
- Implementation writes tests first, then code
See references/testing-anti-patterns.md for detailed anti-patterns and gate functions.
Test Pyramid
/\
/ \ E2E Tests (10%)
/----\ Slow, expensive, few
/ \
/--------\ Integration Tests (20%)
/ \ Medium speed, focused
/------------\
/ \ Unit Tests (70%)
/________________\ Fast, isolated, many
What ships with it
5 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.
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.
- 1mo ago First seen · 280 lines · 40 tokens per session scan A 083b4baf1606
testing-patterns is a skill published in the GitHub repository groupzer0/vs-code-agents (292 stars, last pushed 9mo ago), licensed MIT. It adds 40 tokens to every session and 1,833 once invoked, about $0.0002 per session on Opus 5.5. 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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