zellij/CONTRIBUTING.md

# Contributing to Zellij

Thanks for considering contributing to Zellij!

**First**: if you're unsure of anything, feel free to ask on our [Discord
server](https://discord.gg/MHV3n76PDq), or on [Matrix](https://matrix.to/#/#zellij_general:matrix.org). We're a friendly and welcoming bunch!

# Code of Conduct

Before contributing please read our [Code of Conduct](CODE_OF_CONDUCT.md) which
all contributors are expected to adhere to.

## Building

To build Zellij, we're using cargo xtask. This is a standalone package shipped
inside the repository, so you don't have to install additional dependencies.

To edit our manpage, the mandown crate (`cargo install --locked
mandown`) is used and the work is done on a markdown file in docs/MANPAGE.md.

Here are some of the commands currently supported by the build system:

```sh
# Format code, build, then run tests and clippy
cargo xtask
# You can also perform these actions individually
cargo xtask format
cargo xtask build
cargo xtask test
# Run Zellij (optionally with additional arguments)
cargo xtask run
cargo xtask run -l strider
# Run Clippy
cargo xtask clippy
# Install Zellij to some directory
cargo xtask install /path/of/zellij/binary
# Publish the zellij and zellij-tile crates
cargo xtask publish
# Update manpage
cargo xtask manpage
```

You can see a list of all commands (with supported arguments) with `cargo xtask
--help`. For convenience, `xtask` may be shortened to `x`: `cargo x build` etc.

To run `install` or `publish`, you'll need the package `binaryen` in the
version `wasm-opt --version` > 97, for it's command `wasm-opt`.

To run `test`, you will need the package `pkg-config` and a version of `openssl`.

## Running the end-to-end tests
Zellij includes some end-to-end tests which test the whole application as a black-box from the outside.
These tests work by running a docker container which contains the Zellij binary, connecting to it via ssh, sending some commands and comparing the output received against predefined snapshots.

<details>
<summary>Should you be a macOS (including m1) user, please follow these commands before. (expand here):</summary>

1. `rustup target add x86_64-unknown-linux-musl`
2. `brew install messense/macos-cross-toolchains/x86_64-unknown-linux-musl`
3. `export CC_x86_64_unknown_linux_musl=$(brew --prefix)/bin/x86_64-unknown-linux-musl-gcc`
4. `export AR_x86_64_unknown_linux_musl=$(brew --prefix)/bin/x86_64-unknown-linux-musl-ar`
5. `export CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER=$CC_x86_64_unknown_linux_musl`
</details>


To run these tests locally, you'll need to have either `docker` or `podman` and also `docker-compose` installed.
Once you do, in the repository root:

1. `docker-compose up -d` will start up the docker container
2. `cargo xtask ci e2e --build` will build the generic linux executable of Zellij in the target folder, which is shared with the container
3. `cargo xtask ci e2e --test` will run the tests

To re-run the tests after you've changed something in the code base, be sure to repeat steps 2 and 3.

## Debugging / Troubleshooting while developing
Zellij uses the excellent [`log`](https://crates.io/crates/log) crate to handle its internal logging. The output of these logs will go to `/$temp_dir/zellij-<UID>/zellij-log/zellij.log` which `$temp_dir` refers to [std::env::temp_dir()](https://doc.rust-lang.org/std/env/fn.temp_dir.html). On most of operating systems it points to `/tmp`, but there are exceptions, such as `/var/folders/dr/xxxxxxxxxxxxxx/T/` for Mac.

Example:
```rust
let my_variable = some_function();
log::info!("my variable is: {:?}", my_variable);
```

Note that the output is truncated at 100KB. This can be adjusted for the purposes of debugging through the `LOG_MAX_BYTES` constant, at the time of writing here: https://github.com/zellij-org/zellij/blob/main/zellij-utils/src/logging.rs#L24

When running Zellij with the `--debug` flag, Zellij will dump a copy of all bytes received over the pty for each pane in: `/$temp_dir/zellij-<UID>/zellij-log/zellij-<pane_id>.log`. These might be useful when troubleshooting terminal issues.

## Testing plugins
Zellij allows the use of the [Singlepass](https://crates.io/crates/wasmer-compiler-singlepass) compiler for wasmer. This can enable great gains in compilation time of plugins in detriment of stability, notably on Arm64 architectures.

To enable the singlepass compiler, use the `singlepass` flag. E.g.:
```sh
cargo xtask run --singlepass
```

## How we treat clippy lints

We currently use clippy in [GitHub Actions](https://github.com/zellij-org/zellij/blob/main/.github/workflows/rust.yml) with the default settings that report only [`clippy::correctness`](https://github.com/rust-lang/rust-clippy#readme) as errors and other lints as warnings because Zellij is still unstable. This means that all warnings can be ignored depending on the situation at that time, even though they are also helpful to keep the code quality.
Since we just cannot afford to manage them, we are always welcome to fix them!

Here is [the detailed discussion](https://github.com/zellij-org/zellij/pull/1090) if you want to see it.

## Looking for something to work on?

If you are new contributor to `Zellij` going through
[beginners][good-first-issue] should be a good start or you can join our public
[Discord server][discord-invite-link], we would be happy to help finding
something interesting to work on and guide through.

[discord-invite-link]: https://discord.gg/feHDHahHCz 
[good-first-issue]: https://github.com/zellij-org/zellij/labels/good%20first%20issue


## Tips for Code Contributions

### Prefer returning `Result`s instead of `unwrap`ing

- Add `use zellij_utils::errors::prelude::*;` to the file
- Make the function return `Result<T>`, with an appropriate `T` (Use `()` if there's nothing to return)
- Append `.context()` to any `Result` you get with a sensible error description (see [the docs][error-docs-context])
- Generate ad-hoc errors with `anyhow!(<SOME MESSAGE>)`
- *Further reading*: [See here][error-docs-result]

### Logging errors

- When there's a `Result` type around, use `.non_fatal()` on that instead of `log::error!`
- When there's a `Err` type around, use `Err::<(), _>(err).non_fatal()`
- Also attach context before logging!
- *Further reading*: [See here][error-docs-logging]

### Adding Concrete Errors, Handling Specific Errors

- Add a new variant to `zellij_utils::errors::ZellijError`, if needed
- Use `anyhow::Error::downcast_ref::<ZellijError>()` to recover underlying errors
- *Further reading*: [See here][error-docs-zellijerror]

[error-docs-context]: https://github.com/zellij-org/zellij/blob/main/docs/ERROR_HANDLING.md#attaching-context
[error-docs-result]: https://github.com/zellij-org/zellij/blob/main/docs/ERROR_HANDLING.md#converting-a-function-to-return-a-result-type
[error-docs-logging]: https://github.com/zellij-org/zellij/blob/main/docs/ERROR_HANDLING.md#logging-errors
[error-docs-zellijerror]: https://github.com/zellij-org/zellij/blob/main/docs/ERROR_HANDLING.md#adding-concrete-errors-handling-specific-errors


## Filing Issues

Bugs and enhancement suggestions are tracked as GitHub issues.

### Lacking API for plugin in Zellij?

If you have a plugin idea, but Zellij still doesn't have API required to make
the plugin consider opening [an issue][plugin-issue] and describing your
requirements.

[plugin-issue]:
https://github.com/zellij-org/zellij/issues/new?assignees=&labels=plugin%20system

### How Do I Submit A (Good) Bug Report?

After you've determined which repository your bug is related to and that the
issue is still present in the latest version of the master branch, create an
issue on that repository and provide the following information:

- Use a **clear and descriptive title** for the issue to identify the problem.
- Explain which **behavior you expected** to see instead and why.
- Describe the exact **steps to reproduce the problem** in as many details as
  necessary.
- When providing code samples, please use [code blocks][code-blocks].

### How Do I Submit A (Good) Enhancement Suggestion?

Instructions are similar to those for bug reports. Please provide the following
information:

- Use a **clear and descriptive title** for the issue to identify the
  suggestion.
- Provide a **description of the suggested enhancement** in as many details as
  necessary.
- When providing code samples, please use [code blocks][code-blocks].

[code-blocks]:
https://help.github.com/articles/creating-and-highlighting-code-blocks/

## Submitting Pull Requests

Instructions are similar to those for bug reports. Please provide the following
information:

- If this is not a trivial fix, consider **creating an issue to discuss first**
  and **later link to it from the PR**.
- Use a **clear and descriptive title** for the pull request.
    - Follow [Conventional Commit
      specification](https://www.conventionalcommits.org/en/v1.0.0/) where
      sufficiently large or impactful change is made.
- Provide a **description of the changes** in as many details as necessary.

Before submitting your pull request, also make sure that the following
conditions are met:

- Your new code **adheres to the code style** through running `cargo fmt`.
- Your new code **passes all existing and new tests** through running `cargo
  test`.