```
https://github.com/taiki-e/cargo-llvm-cov
cargo llvm-cov --html
cargo llvm-cov --lcov --output-path lcov.info
open ./target/llvm-cov/html/index.html
Only directory: cargo llvm-cov --html -- --include 'src/flatzinc/*' - does not work.
cargo llvm-cov --html --ignore-filename-regex '^(?!src/flatzinc/)'
cargo llvm-cov --html --ignore-filename-regex '(src/(?!flatzinc)|tests|examples|benchmarks|debug)'
cargo llvm-cov --html --ignore-filename-regex '(tests/|examples/|benchmarks/|debug/)' --output-dir target/llvm-cov
```