ci: add code coverage

.github/codecov.yml

@@ -0,0 +1,43 @@
+coverage:
+  status:
+    project:
+      default:
+        # basic
+        target: auto
+        threshold: 1%
+        base: auto
+        # advanced
+        branches:
+          - main
+        if_ci_failed: error
+        informational: false
+        only_pulls: false
+
+    patch:
+      default:
+        # basic
+        target: auto
+        threshold: 1%
+        base: auto
+        # advanced
+        branches:
+          - main
+        if_ci_failed: error
+        informational: false
+        only_pulls: false
+
+ignore:
+  - "**/benches/**/*"  # Ignore benchmarks
+  - "**/*_test.rs"  # Ignore test files
+  - "**/tests/**/*" # Ignore test directories
+
+github_checks:
+  annotations: true
+
+comment:
+  layout: "diff, flags, files"
+  behavior: default
+  require_changes: false
+  require_base: false
+  require_head: true
+  hide_project_coverage: false 

.github/workflows/ci.yml

@@ -62,6 +62,30 @@ jobs:
           RUSTDOCFLAGS: -D warnings
         run: cargo doc --no-deps --all-features
 
+  coverage:
+    name: Code Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: nightly
+          components: llvm-tools-preview
+      - uses: Swatinem/rust-cache@v2
+        with:
+          cache-on-failure: "true"
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: Generate code coverage
+        run: cargo llvm-cov --all-features --workspace --branch --lcov --output-path lcov.info
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          files: lcov.info
+          fail_ci_if_error: true
+          token: ${{ secrets.CODECOV_TOKEN }}
+          slug: hyperion-mc/hyperion
+
   test:
     name: Tests (${{ matrix.os }})
     strategy: