ci: enable codecov.io reports

.github/workflows/rust.yml

@@ -265,3 +265,45 @@ jobs:
         run: cargo miri test --no-fail-fast --all-features
         env:
           MIRIFLAGS: -Zmiri-disable-isolation
+
+  coverage:
+    if: github.event_name == 'push' || github.event_name == 'schedule' || github.event.pull_request.head.repo.full_name != github.repository
+
+    name: Code coverage
+    runs-on: ubuntu-latest
+    needs: ["check"]
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+      - name: Checkout source
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@683b588c487a69d01f6c6ddf40f036ff682cc2c8 # master
+        with:
+          # doctest coverage requires nightly
+          toolchain: nightly
+          components: llvm-tools-preview
+
+      - name: Cache Cargo registry
+        uses: Swatinem/rust-cache@d1527c8f67ef9af357290475d4af4b0fab8f12e0 # v2.9.3
+        with:
+          shared-key: 'rust-ci'
+          cache-bin: 'false'
+          save-if: 'false'
+
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@8cca0918f8471c33515202b73f56ab27f2bed283 # v2.87.29
+        with:
+          tool: cargo-llvm-cov
+
+      - name: Generate code coverage
+        run: cargo llvm-cov --all-features --doctests --lcov --output-path lcov.info
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f # v6.0.2
+        with:
+          use_oidc: ${{ !github.event.pull_request.head.repo.fork }}
+          files: lcov.info
+          fail_ci_if_error: true

README.md

@@ -3,6 +3,7 @@
 [![Rust CI](https://github.com/google/dtoolkit/actions/workflows/rust.yml/badge.svg)](https://github.com/google/dtoolkit/actions/workflows/rust.yml)
 [![crates.io](https://img.shields.io/crates/v/dtoolkit.svg)](https://crates.io/crates/dtoolkit)
 [![Documentation](https://docs.rs/dtoolkit/badge.svg)](https://docs.rs/dtoolkit)
+[![codecov](https://codecov.io/gh/google/dtoolkit/graph/badge.svg)](https://codecov.io/gh/google/dtoolkit)
 
 A library for parsing and manipulating Flattened Device Tree (FDT) blobs.