build: add GitHub Action for code coverage

PR-URL: https://github.com/nodejs/node/pull/35653
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

.github/workflows/coverage-linux.yml

@@ -0,0 +1,41 @@
+# TODO(bcoe): add similar job for Windows coverage.
+name: coverage-linux
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+env:
+  PYTHON_VERSION: 3.9
+  FLAKY_TESTS: dontcare
+
+jobs:
+  # TODO(bcoe): add support for C++ coverage.
+  coverage-linux:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python ${{ env.PYTHON_VERSION }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+      - name: Environment Information
+        run: npx envinfo
+      - name: Build
+        run: make build-ci -j2 V=1 CONFIG_FLAGS="--error-on-warn"
+      # TODO(bcoe): fix the couple tests that fail with the inspector enabled.
+      # The cause is most likely coverage's use of the inspector.
+      - name: Test
+        run: NODE_V8_COVERAGE=coverage/tmp make run-ci -j2 V=1 TEST_CI_ARGS="-p dots" || exit 0
+      - name: Report
+        run: npx c8 report --check-coverage
+      - name: Output file count
+        run: ls -l coverage/tmp/ | wc -l
+      - name: Clean tmp
+        run: rm -rf coverage/tmp
+      - name: Upload
+        uses: codecov/codecov-action@v1
+        with:
+          directory: ./coverage

.nycrc

@@ -1,7 +1,21 @@
 {
   "exclude": [
-    "**/internal/process/write-coverage.js"
+    "coverage/**",
+    "test/**",
+    "tools/**",
+    "benchmark/**",
+    "deps/**"
   ],
-  "compact": false,
-  "reporter": ["html", "text"]
+  "reporter": [
+    "html",
+    "text",
+    "lcov"
+  ],
+  "lines": 95,
+  "branches": "93",
+  "statements": "95",
+  "temp-directory": "coverage/tmp",
+  "omit-relative": false,
+  "resolve": "./lib",
+  "wrapper-length": 0
 }