coreutils/DEVELOPER_INSTRUCTIONS.md

Code Coverage Report Generation

Code coverage report can be generated using grcov.

Using Nightly Rust

To generate gcov-based coverage report

$ export CARGO_INCREMENTAL=0
$ export RUSTFLAGS="-Zprofile -Ccodegen-units=1 -Copt-level=0 -Clink-dead-code -Coverflow-checks=off -Zpanic_abort_tests -Cpanic=abort"
$ export RUSTDOCFLAGS="-Cpanic=abort"
$ cargo build <options...> # e.g., --features feat_os_unix
$ cargo test <options...> # e.g., --features feat_os_unix test_pathchk
$ grcov . -s . --binary-path ./target/debug/ -t html --branch --ignore-not-existing --ignore build.rs --excl-br-line "^\s*((debug_)?assert(_eq|_ne)?\#\[derive\()" -o ./target/debug/coverage/
$ # open target/debug/coverage/index.html in browser

if changes are not reflected in the report then run cargo clean and run the above commands.

Using Stable Rust

If you are using stable version of Rust that doesn't enable code coverage instrumentation by default then add -Z-Zinstrument-coverage flag to RUSTFLAGS env variable specified above.

pre-commit hooks

A configuration for pre-commit is provided in the repository. It allows automatically checking every git commit you make to ensure it compiles, and passes clippy and rustfmt without warnings.

To use the provided hook:

1. Install pre-commit
2. Run pre-commit install while in the repository directory

Your git commits will then automatically be checked. If a check fails, an error message will explain why, and your commit will be canceled. You can then make the suggested changes, and run git commit ... again.

Using Clippy

The msrv key in the clippy configuration file clippy.toml is used to disable lints pertaining to newer features by specifying the minimum supported Rust version (MSRV). However, this key is only supported on nightly. To invoke clippy without errors, use cargo +nightly clippy. In order to also check tests and non-default crate features, use cargo +nightly clippy --all-targets --all-features.