gha: collate and calculate coverage for all test runs

Signed-off-by: Aleksa Sarai <[email protected]>

.github/workflows/ci.yml

@@ -11,14 +11,29 @@ on:
     - cron: "30 10 * * 0"
 
 jobs:
-  test:
+  test-windows:
+    strategy:
+      matrix:
+        go-version:
+          - "1.21"
+          - "1.22"
+          - "^1"
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v4
+        with:
+          go-version: ${{ matrix.go-version }}
+      - name: unit tests
+        run: go test -v -cover ./...
+
+  test-unix:
     strategy:
       fail-fast: false
       matrix:
         os:
           - ubuntu-latest
           - macos-latest
-          - windows-latest
         go-version:
           - "1.21"
           - "1.22"
@@ -33,9 +48,62 @@ jobs:
       - uses: actions/setup-go@v4
         with:
           go-version: ${{ matrix.go-version }}
+      - name: mkdir gocoverdir
+        run: |
+          GOCOVERDIR="$(mktemp -d gocoverdir.XXXXXXXX)"
+          echo "GOCOVERDIR=$GOCOVERDIR" >>"$GITHUB_ENV"
       - name: unit tests
-        run: go test -v -cover ./...
-      # TODO: Merge the code coverage stats from both runs...
+        run: |
+          GOCOVERDIR="$GOCOVERDIR/nonroot"
+          mkdir -p "$GOCOVERDIR"
+          go test -v -cover -test.gocoverdir="$GOCOVERDIR" ./...
       - name: unit tests (root)
         if: ${{ ! startsWith(matrix.os, 'windows-') }}
-        run: sudo go test -v -cover ./...
+        run: |
+          GOCOVERDIR="$GOCOVERDIR/root"
+          mkdir -p "$GOCOVERDIR"
+          sudo go test -v -cover -test.gocoverdir="$GOCOVERDIR" ./...
+      - name: upload coverage
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-${{ runner.os }}-${{ github.job }}-${{ strategy.job-index }}
+          path: ${{ env.GOCOVERDIR }}
+
+  coverage:
+    runs-on: ubuntu-latest
+    needs:
+      - test-windows
+      - test-unix
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v4
+        with:
+          go-version: "^1"
+      - name: download all coverage
+        uses: actions/download-artifact@v4
+        with:
+          path: coverage
+      - name: generate coverage list
+        run: |
+          GOCOVERDIRS="$(printf '%s,' gocoverdir.*/* | sed 's|,$||')"
+          echo "GOCOVERDIRS=$GOCOVERDIRS" >>"$GITHUB_ENV"
+          FULLCOVERAGE_FILE="$(mktemp fullcoverage.XXXXXXXX)"
+          echo "FULLCOVERAGE_FILE=$FULLCOVERAGE_FILE" >>"$GITHUB_ENV"
+      - name: compute coverage
+        run: go tool covdata percent -i "$GOCOVERDIRS"
+      - name: compute func coverage
+        run: go tool covdata func -i "$GOCOVERDIRS"
+      - name: merge coverage
+        run: |
+          go tool covdata textfmt -i "$GOCOVERDIRS" -o "$FULLCOVERAGE_FILE"
+          go tool cover -html="$FULLCOVERAGE_FILE" -o "$FULLCOVERAGE_FILE.html"
+      - name: upload merged coverage
+        uses: actions/upload-artifact@v4
+        with:
+          name: fullcoverage-${{ github.job }}
+          path: ${{ env.FULLCOVERAGE_FILE }}
+      - name: upload coverage html
+        uses: actions/upload-artifact@v4
+        with:
+          name: fullcoverage-${{ github.job }}.html
+          path: ${{ env.FULLCOVERAGE_FILE }}.html