Add code coverage to ci

.gitea/images/Dockerfile

@@ -1,6 +1,12 @@
 FROM docker.io/library/rust:1.75
 
-RUN rustup component add clippy rustfmt
+RUN rustup component add \
+  clippy \
+  llvm-tools-preview \
+  rustfmt
+
+RUN cargo install \
+  grcov
 
 RUN apt-get update && apt-get install -y \
   beets \

.gitea/scripts/coverage.py

@@ -0,0 +1,23 @@
+import argparse
+import json
+
+
+def main(coverage_file, fail_under):
+    with open(coverage_file, encoding="utf-8") as f:
+        coverage_json = json.load(f)
+    coverage = float(coverage_json["message"][:-1])
+    return coverage >= fail_under
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Check coverage output by grcov")
+
+    parser.add_argument("--coverage-file", type=str, required=True,
+                        help="Path to the coverage.json file output by grcov")
+    parser.add_argument("--fail-under", type=float, default=100.,
+                        help="Threshold under which coverage is insufficient")
+
+    args = parser.parse_args()
+
+    if not main(args.coverage_file, args.fail_under):
+        exit(2)

.gitea/workflows/gitea-ci.yaml

@@ -7,8 +7,10 @@ on:
     branches: [ main ]
 
 env:
-  CARGO_TERM_COLOR: always
   BEETSDIR: ./
+  CARGO_TERM_COLOR: always
+  LLVM_PROFILE_FILE: target/debug/profraw/musichoard-%p-%m.profraw
+  RUSTFLAGS: -C instrument-coverage
 
 jobs:
   build_and_test:
@@ -18,6 +20,21 @@ jobs:
       - uses: actions/checkout@v3
       - run: cargo build --verbose --all-features --all-targets
       - run: cargo test --verbose --all-features --all-targets --no-fail-fast
+      - run: >-
+          grcov codecov/debug/profraw
+              --binary-path ./target/debug/
+              --output-types html
+              --source-dir .
+              --ignore-not-existing
+              --ignore "tests/*"
+              --ignore "src/main.rs"
+              --excl-start "GRCOV_EXCL_START|mod tests \{"
+              --excl-stop "GRCOV_EXCL_STOP"
+              --output-path ./target/debug/coverage/
+      - run: >-
+          python3 .gitea/scripts/coverage.py
+              --coverage-file ./target/debug/coverage/coverage.json
+              --fail-under 100.00
 
   lint:
     name: Lint