How to Block a Merge When Coverage Drops on a Pull Request in GitHub Actions

Exit non-zero when coverage falls below the floor, then mark that job a required status check.

Run coverage with a minimum threshold (your runner can enforce it, or compare the percentage yourself), exit 1 on a drop, and require the job in branch protection.

Steps

• Run tests with coverage and a known floor.
• exit 1 when the percentage is below the floor.
• Make the job a required check in branch protection.

Workflow

jobs:
  coverage-gate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci
      - name: Enforce coverage floor
        run: |
          npm test -- --coverage --coverageReporters=json-summary
          PCT=$(node -p "require('./coverage/coverage-summary.json').total.lines.pct")
          echo "Lines: $PCT%"
          awk "BEGIN { exit ($PCT < 80) }" || { echo "Coverage below 80%"; exit 1; }

Gotchas

• A workflow can only block a merge once the job is added as a required status check in branch protection.
• Jest also supports coverageThreshold in config to fail the test run directly without the awk check.

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