Add coverage in CI

.github/workflows/l1-contracts-ci.yaml

@@ -145,3 +145,73 @@ jobs:
 
       - name: Compare
         run: diff tools/data/Verifier.sol l1-contracts/contracts/state-transition/Verifier.sol
+
+  coverage:
+    defaults:
+      run:
+        working-directory: l1-contracts
+    needs: [build, lint]
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout the repository
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Use Foundry
+        uses: foundry-rs/foundry-toolchain@v1
+
+      - name: Use Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: 18.18.0
+          cache: yarn
+
+      - name: Install dependencies
+        run: yarn
+
+      - name: Restore artifacts cache
+        uses: actions/cache/restore@v3
+        with:
+          fail-on-cache-miss: true
+          key: artifacts-l1-${{ github.sha }}
+          path: |
+            l1-contracts/artifacts
+            l1-contracts/cache
+            l1-contracts/typechain
+
+      - name: Run coverage
+        run: FOUNDRY_PROFILE=default yarn test:foundry && FOUNDRY_PROFILE=default yarn coverage:foundry --report summary --report lcov
+
+      # To ignore coverage for certain directories modify the paths in this step as needed. The
+      # below default ignores coverage results for the test and script directories. Alternatively,
+      # to include coverage in all directories, comment out this step. Note that because this
+      # filtering applies to the lcov file, the summary table generated in the previous step will
+      # still include all files and directories.
+      # The `--rc lcov_branch_coverage=1` part keeps branch info in the filtered report, since lcov
+      # defaults to removing branch info.
+      - name: Filter directories
+        run: |
+          sudo apt update && sudo apt install -y lcov
+          lcov --remove lcov.info 'test/*' 'contracts/dev-contracts/*' 'lib/*' --output-file lcov.info --rc lcov_branch_coverage=1
+
+      # This step posts a detailed coverage report as a comment and deletes previous comments on
+      # each push. The below step is used to fail coverage if the specified coverage threshold is
+      # not met. The below step can post a comment (when it's `github-token` is specified) but it's
+      # not as useful, and this action cannot fail CI based on a minimum coverage threshold, which
+      # is why we use both in this way.
+      - name: Post coverage report
+        if: github.event_name == 'pull_request' # This action fails when ran outside of a pull request.
+        uses: romeovs/lcov-reporter-action@v0.3.1
+        with:
+          delete-old-comments: true
+          lcov-file: ./l1-contracts/lcov.info
+          github-token: ${{ secrets.GITHUB_TOKEN }} # Adds a coverage summary comment to the PR.
+
+      - name: Verify minimum coverage
+        uses: zgosalvez/github-actions-report-lcov@v2
+        with:
+          coverage-files: ./l1-contracts/lcov.info
+          working-directory: l1-contracts
+          minimum-coverage: 85 # Set coverage threshold.