coverage-guard

# Coverage Guard Mode When activated, checks coverage after test runs and warns if it drops below the configured threshold. ## What It Does After any test execution (via Bash tool), compares coverage to the threshold in config.json. Warns (doesn't block) if coverage decreased. ## Activation ``` /coverage-guard ``` ## Configuration Edit `config.json` in this skill directory to set thresholds: ```json { "thresholds": { "statements": 80, "branches": 70, "functions": 75, "lines": 80 }, "coverageCommand": "npx jest --coverage --coverageReporters=json-summary", "coverageFile": "coverage/coverage-summary.json" } ``` ## Hook Configuration ```json { "hooks": { "PostToolUse": [ { "matcher": "Bash", "hook": ".claude/skills/coverage-guard/scripts/check-coverage.sh", "condition": "command contains 'jest' OR command contains 'vitest' OR command contains 'npm test'" } ] } } ``` ## Enforcement Logic ```bash #!/bin/bash # check-coverage.sh COVERAGE_FILE="coverage/coverage-summary.json" THRESHOLD=80 if [ -f "$COVERAGE_FILE" ]; then STATEMENTS=$(jq '.total.statements.pct' "$COVERAGE_FILE") BRANCHES=$(jq '.total.branches.pct' "$COVERAGE_FILE") if (( $(echo "$STATEMENTS < $THRESHOLD" | bc -l) )); then echo "WARNING: Statement coverage ($STATEMENTS%) below threshold ($THRESHOLD%)" echo "Coverage dropped — check which files lost coverage." fi if (( $(echo "$BRANCHES < 70" | bc -l) )); then echo "WARNING: Branch coverage ($BRANCHES%) below 70%" fi fi ``` ## Gotchas - Coverage check runs AFTER the test command — if tests crash, no coverage report is generated - Coverage-summary.json must be configured as a reporter — default Jest config may not include it - Threshold comparisons use floating point — `79.999%` will trigger below `80%` threshold - Branch coverage is typically 10-15% lower than line coverage — set thresholds accordingly