Add code coverage job (#8)

* Add code coverage job

* Use cargo-llvm-cov

* Add coverage report file

* Clean up

* Clean up

.github/workflows/rust-ci.yml

@@ -3,6 +3,7 @@ on:
     push:
       branches: [main]
     pull_request:
+      branches: [main]
 jobs:
   check:
     runs-on: ubuntu-latest
@@ -41,3 +42,22 @@ jobs:
         - uses: dtolnay/rust-toolchain@stable
         - name: cargo test
           run: cargo test
+  coverage:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: llvm-tools-preview
+      - name: cargo install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: cargo generate-lockfile
+        if: hashFiles('Cargo.lock') == ''
+        run: cargo generate-lockfile
+      - name: cargo llvm-cov
+        run: cargo llvm-cov --locked --all-features --lcov --output-path lcov.info
+      - name: Upload to codecov.io
+        uses: codecov/codecov-action@v3
+        with:
+          files: lcov.info
+          fail_ci_if_error: true