github: Report code coverage

Closes #4

Author: ernestask

.github/workflows/primary.yml

@@ -42,10 +42,37 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: Swatinem/rust-cache@v1
-      - name: Build
-        run: cargo build --tests --verbose
-      - name: Run tests
-        run: cargo test --verbose
+      - uses: actions-rs/toolchain@v1
+        with:
+          components: llvm-tools-preview
+          override: true
+          toolchain: stable
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --all-features --no-fail-fast
+        env:
+          LLVM_PROFILE_FILE: "nldl-%p-%m.profraw"
+          RUSTFLAGS: '-Cinstrument-coverage'
+      - use: actions-rs/cargo@v1
+        with:
+          command: install
+          args: grcov
+      - id: coverage
+        run: |
+          grcov \
+            --branch \
+            --ignore-not-existing \
+            --llvm \
+            --binary-path=target/debug/ \
+            --output-path=target/debug/lcov.info \
+            --output-type=lcov \
+            --source-dir=. \
+            .
+          echo '::set-output name=report::target/debug/lcov.info'
+      - uses: codecov/codecov-action@v2
+        with:
+          files: ${{ steps.coverage.outputs.report }}
 
   check-readme:
     runs-on: ubuntu-latest