Coverage Ratcheting Skill

Enforce a coverage ratchet: coverage for each package must never decrease from its high-water mark.

Trigger Conditions

• •Test suite run completes with coverage data
• •PR is submitted for review
• •Coverage thresholds are checked in CI
• •User invokes with "coverage check" or "coverage-ratcheting"

Input Contract

• •Required: Current coverage data (from go test -cover)
• •Optional: Previous coverage baseline for comparison

Output Contract

• •Per-package coverage percentages
• •Coverage delta from baseline (improved / unchanged / regressed)
• •Packages below minimum threshold per rule 123
• •Ratchet violations (packages that decreased from high-water mark)
• •Recommended test additions to close gaps

Tool Permissions

• •Read: Test files, coverage reports, source files
• •Write: Coverage baseline file (if updating)
• •Shell: Run go test -coverprofile
• •Search: Grep for untested functions

Execution Steps

1. •Run tests with coverage: Execute go test -coverprofile=coverage.out ./...
2. •Parse coverage: Extract per-package and per-function coverage
3. •Compare to baseline: Check each package against its previous high-water mark
4. •Check thresholds: Verify each package meets minimum thresholds per rule 123
5. •Identify regressions: Flag any package where coverage decreased
6. •Recommend: For packages below threshold, identify the uncovered functions
7. •Update baseline: If coverage improved, update the high-water mark

Minimum Thresholds (from rule 123)

• •internal/service/ — 90%
• •internal/repository/ — 85%
• •internal/handler/ — 80%
• •internal/middleware/ — 80%
• •internal/models/ — 75%

References

• •.cursor/rules/123-test-requirement-matrix.mdc