How do I install the Scenario Testing skill?

Run npx skillmds@latest add aiskillstore/scenario-testing in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Scenario Testing safe to use?

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Which AI agents work with Scenario Testing?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Scenario Testing free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Scenario Testing?

aiskillstore (@aiskillstore) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Scenario Testing by aiskillstore — Agent Skill

Name: Scenario Testing
Rating: 4.666666666666667 (3 reviews)
Author: aiskillstore

Scenario Testing

This skill should be used when writing tests, validating features, or needing to verify code works. Triggers on "write tests", "add test coverage", "validate feature", "integration test", "end-to-end", "e2e test", "mock", "unit test". Enforces scenario-driven testing with real dependencies in .scratch/ directory.

aiskillstore Updated Sep 8, 2026

File contents

Scenario-Driven Testing for AI Code Generation

Core Principle

The Iron Law: "NO FEATURE IS VALIDATED UNTIL A SCENARIO PASSES WITH REAL DEPENDENCIES"

Mocks create false confidence. Only scenarios exercising real systems validate that code works.

The Truth Hierarchy

Scenario tests (real system, real data) = truth
Unit tests (isolated) = human comfort only
Mocks = lies hiding bugs

As stated in the principle: "A test that uses mocks is not testing your system. It's testing your assumptions about how dependencies behave."

When to Use This Skill

Validating new functionality
Before declaring work complete
When tempted to use mocks
After fixing bugs requiring verification
Any time you need to prove code works

Required Practices

1. Write Scenarios in `.scratch/`

Use any language appropriate to the task
Exercise the real system end-to-end
Zero mocks allowed
Must be in .gitignore (never commit)

2. Promote Patterns to `scenarios.jsonl`

Extract recurring scenarios as documented specifications
One JSON line per scenario
Include: name, description, given/when/then, validates
This file IS committed

3. Use Real Dependencies

External APIs must hit actual services (sandbox/test mode acceptable). Mocking any dependency invalidates the scenario.

4. Independence Requirement

Each scenario must run standalone without depending on prior executions. This enables:

Parallel execution
Prevents hidden ordering dependencies
Reliable CI/CD integration

What Makes a Scenario Invalid

A scenario is invalid if it:

Contains any mocks whatsoever
Uses fake data instead of real storage
Depends on another scenario running first
Never actually executed to verify it passes

Common Violations to Avoid

Reject these rationalizations:

"Just a quick unit test..." - Unit tests don't validate features
"Too simple for end-to-end..." - Integration breaks simple things
"I'll mock for speed..." - Speed doesn't matter if tests lie
"I don't have API credentials..." - Ask your human partner for real ones

Definition of Done

A feature is complete only when:

✅ A scenario in .scratch/ passes with zero mocks
✅ Real dependencies are exercised
✅ .scratch/ remains in .gitignore
✅ Robust patterns extracted to scenarios.jsonl

Example Workflow

Write scenario - Create .scratch/test-user-registration.py
Use real dependencies - Hit real database, real auth service (test mode)
Run and verify - Execute scenario, confirm it passes
Extract pattern - Document in scenarios.jsonl
Keep .scratch ignored - Never commit scratch scenarios

Why This Matters

Unit tests verify isolated logic
Integration tests verify components work together
Scenario tests verify the system actually works

Only scenario tests prove your feature delivers value to users.

---name: scenario-testingdescription: This skill should be used when writing tests, validating features, or needing to verify code works. Triggers on "write tests", "add test coverage", "validate feature", "integration test", "end-to-end", "e2e test", "mock", "unit test". Enforces scenario-driven testing with real dependencies in .scratch/ directory.---# Scenario-Driven Testing for AI Code Generation## Core Principle**The Iron Law**: "NO FEATURE IS VALIDATED UNTIL A SCENARIO PASSES WITH REAL DEPENDENCIES"Mocks create false confidence. Only scenarios exercising real systems validate that code works.## The Truth Hierarchy1. **Scenario tests** (real system, real data) = **truth**2. **Unit tests** (isolated) = human comfort only3. **Mocks** = lies hiding bugsAs stated in the principle: "A test that uses mocks is not testing your system. It's testing your assumptions about how dependencies behave."## When to Use This Skill- Validating new functionality- Before declaring work complete- When tempted to use mocks- After fixing bugs requiring verification- Any time you need to prove code works## Required Practices### 1. Write Scenarios in `.scratch/`- Use any language appropriate to the task- Exercise the real system end-to-end- Zero mocks allowed- Must be in `.gitignore` (never commit)### 2. Promote Patterns to `scenarios.jsonl`- Extract recurring scenarios as documented specifications- One JSON line per scenario- Include: name, description, given/when/then, validates- This file IS committed### 3. Use Real DependenciesExternal APIs must hit actual services (sandbox/test mode acceptable). Mocking any dependency invalidates the scenario.### 4. Independence RequirementEach scenario must run standalone without depending on prior executions. This enables:- Parallel execution- Prevents hidden ordering dependencies- Reliable CI/CD integration## What Makes a Scenario InvalidA scenario is invalid if it:- Contains any mocks whatsoever- Uses fake data instead of real storage- Depends on another scenario running first- Never actually executed to verify it passes## Common Violations to AvoidReject these rationalizations:- **"Just a quick unit test..."** - Unit tests don't validate features- **"Too simple for end-to-end..."** - Integration breaks simple things- **"I'll mock for speed..."** - Speed doesn't matter if tests lie- **"I don't have API credentials..."** - Ask your human partner for real ones## Definition of DoneA feature is complete only when:1. ✅ A scenario in `.scratch/` passes with zero mocks2. ✅ Real dependencies are exercised3. ✅ `.scratch/` remains in `.gitignore`4. ✅ Robust patterns extracted to `scenarios.jsonl`## Example Workflow1. **Write scenario** - Create `.scratch/test-user-registration.py`2. **Use real dependencies** - Hit real database, real auth service (test mode)3. **Run and verify** - Execute scenario, confirm it passes4. **Extract pattern** - Document in `scenarios.jsonl`5. **Keep .scratch ignored** - Never commit scratch scenarios## Why This Matters- **Unit tests** verify isolated logic- **Integration tests** verify components work together- **Scenario tests** verify the system actually worksOnly scenario tests prove your feature delivers value to users.

Frequently asked questions