Try something

Author: gleocadie

.github/workflows/coverage.yml

@@ -35,6 +35,13 @@ jobs:
         with:
           cache-targets: true # cache build artifacts
           cache-bin: true # cache the ~/.cargo/bin directory
+      - name: Verify bin_tests contribution to coverage
+        run: |
+          cargo llvm-cov nextest --no-report --package bin_tests
+          echo "=== Profraw files created ==="
+          find target/llvm-cov-target -name "*.profraw" -ls
+          cargo llvm-cov report --package bin_tests --summary-only
+          cargo clean
       - name: Generate code coverage (including doc tests)
         run: |
           cargo llvm-cov --all-features --workspace --no-report nextest

bin_tests/src/lib.rs

@@ -66,6 +66,13 @@ fn inner_build_artifact(c: &ArtifactsBuild) -> anyhow::Result<PathBuf> {
         build_cmd.env("RUSTFLAGS", rustflags);
     }
 
+    // Pass CARGO_TARGET_DIR to ensure we build in the same target directory
+    // that cargo-llvm-cov is using (e.g., target/llvm-cov-target/)
+    // Without this, cargo build would use target/debug/ and miss instrumentation
+    if let Ok(target_dir) = env::var("CARGO_TARGET_DIR") {
+        build_cmd.env("CARGO_TARGET_DIR", target_dir);
+    }
+
     let output = build_cmd.output().unwrap();
     if !output.status.success() {
         anyhow::bail!(