fusengine The adoption decision is rule-based: adopt B if its accuracy is at least equal with acceptable token cost, consider B as a trade-off if accuracy improves >10% despite <20% token regression, otherwise keep A or iterate. Requires a minimum of 20 test cases with 15-20% edge cases for statistical significance.
Prompt Testing
Skill for testing, comparing, and measuring prompt performance.
References
- metrics.md - Load when: defining or scoring Quality/Efficiency/Robustness/UX metrics with thresholds and calculation formulas
- methodology.md - Load when: running a full A/B test (hypothesis, dataset sizing, statistical significance, common pitfalls)
- templates.md - Load when: writing a test dataset JSON or an A/B test report
Testing Workflow
1. DEFINE
└── Test objective
└── Metrics to measure
└── Success criteria
2. PREPARE
└── Variants A and B
└── Test dataset
└── Baseline (if existing)
3. EXECUTE
└── Run on dataset
└── Collect results
└── Document observations
4. ANALYZE
└── Calculate metrics
└── Compare variants
└── Identify patterns
5. DECIDE
└── Recommendation
└── Statistical confidence
└── Next iterations
Performance Metrics
Quality
| Metric | Description | Calculation |
|---|---|---|
| Accuracy | Correct responses | Correct / Total |
| Compliance | Format adherence | Compliant / Total |
| Consistency | Response stability | 1 - Variance |
| Relevance | Meeting the need | Average score (1-5) |
Efficiency
| Metric | Description | Calculation |
|---|---|---|
| Tokens Input | Prompt size | Token count |
| Tokens Output | Response size | Token count |
| Latency | Response time | ms |
| Cost | Price per request | Tokens × Price |
Robustness
| Metric | Description | Calculation |
|---|---|---|
| Edge Cases | Edge case handling | Passed / Total |
| Jailbreak Resist | Bypass resistance | Blocked / Attempts |
| Error Recovery | Error recovery | Recovered / Errors |
For full definitions, thresholds, and the UX metrics category, see metrics.md. For the test dataset and report formats, see templates.md.
Commands
# Create a test
/prompt test create --name "Test v1" --dataset tests.json
# Run an A/B test
/prompt test run --a prompt_a.md --b prompt_b.md --dataset tests.json
# View results
/prompt test results --id test_001
# Compare two tests
/prompt test compare --tests test_001,test_002
Decision Criteria
When to adopt variant B?
IF:
- Accuracy B >= Accuracy A
AND (Tokens B <= Tokens A * 1.1 OR accuracy improvement > 5%)
AND no regression on edge cases
THEN:
→ Adopt B
ELSE IF:
- Accuracy improvement > 10%
AND token regression < 20%
THEN:
→ Consider B (acceptable trade-off)
ELSE:
→ Keep A or iterate
Best Practices
- Minimum 20 test cases for significance
- Include edge cases (15-20% of dataset)
- Test multiple runs for consistency
- Document hypotheses before testing
- Version the prompts being tested