Contributing

Contributors are very welcome! No contribution is too small and all contributions are valued.

Some suggestions to get started:

You can look at the good first issue label on the issue tracker.
Help with packaging on various distributions needed!
To use print debugging to the Helix log file, you must:
Print using log::info!, warn!, or error!. (log::info!("helix!"))
Pass the appropriate verbosity level option for the desired log level. (hx -v <file> for info, more vs for higher verbosity)
Want to display the logs in a separate file instead of using the :log-open command in your compiled Helix editor? Start your debug version with cargo run -- --log foo.log and in a new terminal use tail -f foo.log
Instead of running a release version of Helix, while developing you may want to run in debug mode with cargo run which is way faster to compile
Looking for even faster compile times? Give a try to mold
If your preferred language is missing, integrating a tree-sitter grammar for it and defining syntax highlight queries for it is straight forward and doesn't require much knowledge of the internals.
If you don't use the Nix development shell and are getting your rust-analyzer binary from rustup, you may need to run rustup component add rust-analyzer. This is because rust-toolchain.toml selects our MSRV for the development toolchain but doesn't download the matching rust-analyzer automatically.

We provide an architecture.md that should give you a good overview of the internals.

Auto generated documentation

Some parts of the book are autogenerated from the code itself, like the list of :commands and supported languages. To generate these files, run

cargo xtask docgen

inside the project. We use xtask as an ad-hoc task runner.

To preview the book itself, install mdbook. Then, run

mdbook serve book

and visit http://localhost:3000.

Testing

Unit tests/Documentation tests

Run cargo test --workspace to run unit tests and documentation tests in all packages.

Integration tests

Integration tests for helix-term can be run with cargo integration-test. Code contributors are strongly encouraged to write integration tests for their code. Existing tests can be used as examples. Helpers can be found in helpers.rs. The log level can be set with the HELIX_LOG_LEVEL environment variable, e.g. HELIX_LOG_LEVEL=debug cargo integration-test.

Contributors using MacOS might encounter Too many open files (os error 24) failures while running integration tests. This can be resolved by increasing the default value (e.g. to 10240 from 256) by running ulimit -n 10240.

Minimum Stable Rust Version (MSRV) Policy

Helix keeps an intentionally low MSRV for the sake of easy building and packaging downstream. We follow Firefox's MSRV policy. Once Firefox's MSRV increases we may bump ours as well, but be sure to check that popular distributions like Ubuntu package the new MSRV version. When increasing the MSRV, update these three places:

the workspace.package.rust-version key in Cargo.toml in the repository root
the env.MSRV key at the top of .github/workflows/build.yml
the toolchain.channel key in rust-toolchain.toml