Test Gap Finder
Turn coverage and mutation evidence into concrete missing-behavior tests.
Get a ranked list of gaps with proposed assertions and evidence.
Free · 2 KB · SKILL.md, instructions and example files. Provide coverage reports, mutation results and the relevant code/tests.
A worked example
A small example to try before using your own data.
Input
{
"code": "allow = actor.tenant_id == record.tenant_id",
"mutant": "allow = True",
"result": "survived",
"existing_test": "same-tenant access only"
}Expected result
Gap: cross-tenant access is untested. Add actor tenant A + record tenant B and assert denial with no mutation. This test should kill the surviving equality-removal mutant.
What to check: Assert denied behavior and absence of data changes; a test that merely repeats the equality expression is insufficient.
Limits: Coverage is a clue, not proof of correctness. Equivalent mutants and unsupported behavior need separate treatment.
Worked example included. Model-specific performance and vendor compatibility have not been benchmarked.
🧠 Why it works
Assert denied behavior and absence of data changes; a test that merely repeats the equality expression is insufficient.
⚙️ How it works
- Map uncovered lines and surviving mutants to observable behavior and affected callers.
- Check whether a surviving mutant is equivalent or outside the supported contract before calling it a gap.
- Prioritize authorization, money, isolation, recovery and other consequential behavior using the actual application context.
- Propose the smallest test with inputs and an outcome that would distinguish correct from faulty behavior.
- Separate demonstrated gaps from hypotheses and record where report coverage is incomplete.
Description
Get a ranked list of gaps with proposed assertions and evidence.
Provide coverage reports, mutation results and the relevant code/tests.
Limits: Coverage is a clue, not proof of correctness. Equivalent mutants and unsupported behavior need separate treatment.
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