Compare runtime behavior between original and migrated repositories to detect behavioral differences, regressions, and semantic changes. Use when validating code migrations, refactorings, language ports, framework upgrades, or any transformation that should preserve behavior. Automatically compares test results, execution traces, API responses, and observable outputs between two repository versions. Provides actionable guidance for fixing deviations and ensuring behavioral equivalence.
85
78%
Does it follow best practices?
Impact
97%
2.62xAverage score across 3 eval scenarios
Passed
No known issues
Optimize this skill with Tessl
npx tessl skill review --optimize ./skills/behavior-preservation-checker/SKILL.mdTest-based comparison workflow
pytest json-report flag
0%
100%
json-report-file flag
0%
100%
compare_test_results.py usage
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50%
Report behavioral_equivalence
50%
100%
Report summary fields
0%
100%
Severity classification
100%
100%
Differences list
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100%
Recommendations list
0%
100%
Separate result files
0%
100%
Variance regression identified
100%
100%
behavior_checker.py orchestrator and report format
behavior_checker.py invocation
41%
66%
behavior_report.json created
100%
100%
Report summary section
20%
100%
passed_original_failed_migrated count
0%
100%
Differences array
0%
100%
Severity on differences
0%
100%
Critical severity regression
0%
100%
Recommendations array
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100%
Guidance on differences
0%
100%
behavioral_equivalence percentage
0%
100%
Workflow log
100%
100%
Property-based testing and multi-method comparison
hypothesis import
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100%
@given decorator used
0%
100%
strategies used
0%
100%
Equivalence assertion in property tests
50%
100%
Multiple comparison methods
100%
100%
Tolerance threshold applied
100%
100%
behavior_report.json present
100%
100%
Report differences populated
100%
100%
Report recommendations
100%
100%
Severity levels present
100%
100%
comparison_notes.md present
100%
100%
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Table of Contents
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