ci(coverage): Switch to cargo-llvm-cov for code coverage

- Updated .github/workflows/code_coverage.yml to use cargo-llvm-cov instead of grcov
- Removed environment variables (RUSTFLAGS, RUSTDOCFLAGS, LLVM_PROFILE_FILE)
- Switched to nightly toolchain for coverage generation
- Enabled coverage_nightly config attribute in lib.rs
- Added coverage(off) attribute to all test modules to exclude them from coverage reports
- Added lint config for coverage_nightly cfg to Cargo.toml
- Also add lcov.info to .gitignore to prevent accidental commits

Author: Copilot

.github/workflows/code_coverage.yml

@@ -1,6 +1,6 @@
 name: Code Coverage
 
-# Generates code coverage reports using grcov and uploads results to Codecov.
+# Generates code coverage reports using cargo-llvm-cov and uploads results to Codecov.
 # Runs on every push and pull request to track test coverage metrics.
 # Uploads coverage data to Codecov for tracking and produces an HTML report artifact for download.
 
@@ -14,38 +14,32 @@ jobs:
   Coverage:
     name: Code Coverage
     runs-on: ubuntu-latest
-    env:
-      RUSTFLAGS: "-Cinstrument-coverage"
-      RUSTDOCFLAGS: "-Cinstrument-coverage"
-      LLVM_PROFILE_FILE: "./target/coverage/%p-%m.profraw"
 
     steps:
       - name: Checkout
         uses: actions/checkout@v6
         with:
           persist-credentials: false
-      - name: Install lcov tools
-        run: sudo apt-get install lcov -y
-      # This action automatically reads and applies rust-toolchain.toml
       - name: Install Rust toolchain
         uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
+          toolchain: nightly
           components: llvm-tools-preview
           cache: true
-      - name: Install grcov
-        run: if [[ ! -e ~/.cargo/bin/grcov ]]; then cargo install grcov; fi
-      - name: Test
-        run: cargo test --all-features
-      - name: Make coverage directory
-        run: mkdir coverage
-      - name: Run grcov
-        run: grcov . --binary-path ./target/debug/ -s . -t lcov --branch --ignore-not-existing --keep-only 'src/**' --ignore 'tests/**' --ignore 'examples/**' -o ./coverage/lcov.info
+      - name: Install cargo-llvm-cov
+        run: cargo install cargo-llvm-cov
+      - name: Generate coverage data
+        run: cargo llvm-cov --all-features --branch --quiet --ignore-filename-regex "test_utils" --lcov --output-path lcov.info
+        env:
+          RUSTFLAGS: "--cfg coverage_nightly"
       - name: Generate HTML coverage report
-        run: genhtml -o coverage-report.html --ignore-errors unmapped ./coverage/lcov.info
+        run: cargo llvm-cov --all-features --branch --quiet --ignore-filename-regex "test_utils" --html
+        env:
+          RUSTFLAGS: "--cfg coverage_nightly"
       - name: Codecov upload
         uses: codecov/codecov-action@5a1091511ad55cbe89839c7260b706298ca349f7
         with:
-          files: ./coverage/lcov.info
+          files: ./lcov.info
           flags: rust
           name: codecov-bdk-wallet
           token: ${{ secrets.CODECOV_TOKEN }}
@@ -54,4 +48,4 @@ jobs:
         uses: actions/upload-artifact@v6
         with:
           name: coverage-report
-          path: coverage-report.html
+          path: target/llvm-cov/html

.gitignore

@@ -9,3 +9,6 @@ Cargo.lock
 *.db
 *.sqlite*
 examples/test_data
+
+# Coverage reports
+lcov.info

Cargo.toml

@@ -16,6 +16,9 @@ rust-version = "1.85.0"
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
 
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(coverage_nightly)'] }
+
 [dependencies]
 bdk_chain = { version = "0.23.1", features = ["miniscript", "serde"], default-features = false }
 bitcoin = { version = "0.32.7", features = ["serde", "base64"], default-features = false }

src/descriptor/checksum.rs

@@ -34,6 +34,7 @@ pub fn calc_checksum(desc: &str) -> Result<String, DescriptorError> {
     }
 }
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod test {
     use super::*;

src/descriptor/dsl.rs

@@ -823,6 +823,7 @@ macro_rules! fragment {
     });
 }
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod test {
     use alloc::string::ToString;

src/descriptor/mod.rs

@@ -609,6 +609,7 @@ impl DescriptorMeta for ExtendedDescriptor {
     }
 }
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod test {
     use alloc::string::ToString;

src/descriptor/policy.rs

@@ -1173,6 +1173,7 @@ impl ExtractPolicy for Descriptor<DescriptorPublicKey> {
     }
 }
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod test {
     use super::*;

src/descriptor/template.rs

@@ -632,6 +632,7 @@ expand_make_bipxx!(legacy, Legacy);
 expand_make_bipxx!(segwit_v0, Segwitv0);
 expand_make_bipxx!(segwit_v1, Tap);
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod test {
     // Test existing descriptor templates to make sure they are expanded to the right descriptors.

src/keys/bip39.rs

@@ -149,6 +149,7 @@ impl<Ctx: ScriptContext> GeneratableKey<Ctx> for Mnemonic {
     }
 }
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod test {
     use super::WordCount;

src/keys/mod.rs

@@ -1041,6 +1041,7 @@ impl fmt::Display for KeyError {
 #[cfg(feature = "std")]
 impl std::error::Error for KeyError {}
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod test {
     use super::*;