ci: add code coverage workflow

.github/workflows/code_coverage.yml

@@ -0,0 +1,49 @@
+name: Code Coverage
+
+on: [push, pull_request]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  Coverage:
+    name: Code Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+      - name: Install Rust toolchain
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          toolchain: nightly-2026-04-09
+          override: true
+          cache: true
+          components: llvm-tools-preview
+      - name: Install cargo-llvm-cov
+        run: if [[ ! -e ~/.cargo/bin/cargo-llvm-cov ]]; then cargo install cargo-llvm-cov; fi
+      - name: Make coverage directory
+        run: mkdir coverage
+      - name: Test and export lcov coverage
+        run: cargo llvm-cov -q --branch --all --ignore-filename-regex "(examples/|tests/)" --all-features --lcov --output-path ./coverage/lcov.info
+        env:
+          RUSTFLAGS: "--cfg coverage_nightly"
+      - name: Generate HTML coverage report
+        run: cargo llvm-cov -q --branch --all --ignore-filename-regex "(examples/|tests/)" --all-features --html
+        env:
+          RUSTFLAGS: "--cfg coverage_nightly"
+      - name: Codecov upload
+        uses: codecov/codecov-action@57e3a136b779b570ffcdbf80b3bdc90e7fab3de2 # v6.0.0
+        with:
+          files: ./coverage/lcov.info
+          flags: rust
+          name: codecov-bdk-tx
+          token: ${{ secrets.CODECOV_TOKEN }}
+          fail_ci_if_error: false
+      - name: Upload artifact
+        uses: actions/upload-artifact@v7
+        with:
+          name: coverage-report
+          path: target/llvm-cov/html

Cargo.toml

@@ -10,6 +10,9 @@ description = "Bitcoin transaction building library."
 license = "MIT OR Apache-2.0"
 readme = "README.md"
 
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(coverage_nightly)'] }
+
 [dependencies]
 miniscript = { version = "12.3.5", default-features = false }
 bdk_coin_select = "0.4.0"

src/finalizer.rs

@@ -162,6 +162,7 @@ impl FinalizeMap {
     }
 }
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod tests {
     use crate::{Finalizer, Output, PsbtParams, Selection, Signer};

src/lib.rs

@@ -1,4 +1,5 @@
 //! `bdk_tx`
+#![cfg_attr(coverage_nightly, feature(coverage_attribute))]
 #![warn(missing_docs)]
 #![no_std]
 

src/selection.rs

@@ -316,6 +316,7 @@ impl Selection {
     }
 }
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod tests {
     use super::*;

src/signer.rs

@@ -66,6 +66,7 @@ impl GetKey for Signer {
     }
 }
 
+#[cfg_attr(coverage_nightly, coverage(off))]
 #[cfg(test)]
 mod test {
     use crate::bitcoin::bip32::ChildNumber;