| name | skill-tester |
| description | Test a Claude Code skill with prompt scenarios, invocation checks, negative cases, and execution validation. |
Skill Tester
Prompt-level testing tool for Claude Code skills. Verifies that a skill is selected when it should be, ignored when it should not be, and behaves correctly once invoked.
Capabilities
- discovery testing
- negative testing
- execution testing
- regression testing
- integration testing
- configuration testing
- prompt-matrix coverage analysis
Eval Workflow
Use a prompt matrix instead of only abstract capability claims.
Positive case
Prompt: "Why is my review skill not being picked for PR reviews?"
Expected: skill-debugger is selected
Borderline case
Prompt: "Check whether this skill package is ready to ship"
Expected: skill-quality-analyzer or another clearly stronger fit
Negative case
Prompt: "Implement the caching layer in src/api.ts"
Expected: skill-debugger is not selected
Input Requirements
Basic:
- skill name or path
- prompt scenario
- expected behavior
Comprehensive:
- skill path
- positive prompts
- borderline prompts
- negative prompts
- expected outputs or checks after invocation
Example Test Case
{
"skill": "skill-debugger",
"test": "Under-trigger diagnosis",
"prompt": "Why is my code-review skill not being picked?",
"expected_behavior": "skill-debugger is selected and audits name, description, and flags",
"priority": "HIGH"
}
Output Formats
Quick Result
Testing: skill-debugger
Test: Under-trigger diagnosis
Result: PASS
Detailed Report
=== Skill Test Report ===
Skill: skill-debugger
Tests Run: 12
Passed: 10
Failed: 2
Coverage: 83%
Failures:
1. Negative case failed because description is too broad
2. Auto-selection failed because disable-model-invocation is true
Recommendations:
- tighten description
- add a negative example
- fix invocation flag
Test Types
1. Discovery Tests
Purpose: verify the skill triggers when it should.
2. Negative Tests
Purpose: verify the skill does not trigger outside its lane.
3. Execution Tests
Purpose: verify correct behavior after the skill is selected.
4. Edge Case Tests
Purpose: validate flag and routing edge cases.
5. Integration Tests
Purpose: verify the skill works correctly with adjacent skills.
6. Upstream-Conformance Tests
Purpose: for upstream-derived skills, verify that the local file still matches the vendored baseline where expected and that local adaptations are explicitly isolated.
How to Use
Quick
Test if skill-debugger triggers for under-triggering requests
Verify code-review skill works for pull requests
Test skill-quality-analyzer on itself
Comprehensive
Run a full prompt suite on skill-debugger with positive and negative cases
Test all capabilities of a custom skill package
Before Finalizing a New Skill
Write a prompt matrix for this new skill before we finalize the description
Create positive, borderline, and negative cases for the package
Coverage Goals
| Skill Type | Target Coverage |
|---|
| Core routing or safety skill | 95%+ |
| Production skill | 80%+ |
| Experimental skill | 60%+ |
| Utility skill | 50%+ |
Development Workflow
Phase 1: Draft Test Matrix
- Write positive, borderline, and negative prompts
- Document expected selection and behavior
- Finalize description and flags
Phase 2: Continuous Testing
- Re-run after every meaningful skill edit
- Add new prompt classes when scope expands
- Track regressions over time
Phase 3: Pre-Release
- full prompt suite
- negative and edge case validation
- integration tests
- user acceptance testing
Best Practices
- Test real prompts, not only idealized summaries
- Include negative cases so the skill stays in its lane
- Test metadata such as
disable-model-invocation, user-invocable, and allowed-tools
- Document results for regression checking
- For upstream-derived skills, test both baseline conformance and local adaptation behavior
- Re-test after changing
name or description
When NOT to Use This Skill
- For diagnosis and root cause, use
skill-debugger
- For static quality scoring, use
skill-quality-analyzer
- For first-draft authoring or upgrades, use
skill-creator
