starship/CONTRIBUTING.md

# Contributing

🚀 Thank you for contributing to starship! 🚀

Please note that this project is released with a [Contributor Code of Conduct](CODE_OF_CONDUCT.md). By contributing to this project you agree to abide by its terms.

If you have any questions that aren't addressed in this document, please don't hesitate to open an issue or drop into our [Discord server](https://discord.gg/8Jzqu3T)! 💬

## Glossary

- **Module**: A component in the prompt giving information based on contextual information from your OS. For example, the `nodejs` module shows the version of NodeJS that is currently installed on your computer, if your current directory is a NodeJS project.

- **Segment**: Smaller sub-components that compose a module. For example, the `symbol` segment in the `nodejs` module contains the character that is shown before the version number (`⬢` by default).

## Philosophy

We aim to make starship as fast, robust and reliable as possible, while also allowing for extensive customization. We do so by leveraging Rust's inherent safety and with thorough cross-platform testing. We also do our best to eliminate unnecessary work when displaying the prompt by reducing repeated work and by using caching to our favor.

If you spot anywhere that we could trim some time or reduce the prompt's workload, we will gladly accept new issues or PRs! 😄

## Architecture

The project begins in [`main.rs`](src/main.rs), where the appropriate `print::` method is called based on which arguments are given to [clap](https://crates.io/crates/clap). When printing the full prompt, we use [rayon](https://crates.io/crates/rayon) to parallelize the computation of modules.

Any styling that is applied to a module is inherited by its segments. Module prefixes and suffixes by default don't have any styling applied to them.

## Environment Variables and external commands

We have custom functions to be able to test our modules better. Here we show you how.

### Environment Variables

To get an environment variable we have special function to allow for mocking of vars. Here's a quick example:

```rust
use super::{Context, Module, RootModuleConfig};

use crate::configs::php::PhpConfig;
use crate::formatter::StringFormatter;
use crate::utils;


pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
   // Here `my_env_var` will be either the contents of the var or the function
   // will exit if the variable is not set.
   let my_env_var = context.get_env("MY_VAR")?;

   // Then you can happily use the value
}
```

## External commands

To run a external command (e.g. to get the version of a tool) and to allow for mocking use the `utils::exec_cmd` function. Here's a quick example:

```rust
use super::{Context, Module, RootModuleConfig};

use crate::configs::php::PhpConfig;
use crate::formatter::StringFormatter;
use crate::utils;


pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
   // Here `my_env_var` will be either the stdout of the called command or the function
   // will exit if the called program was not installed or could not be run.
   let output = utils::exec_cmd("my_command", &["first_arg", "second_arg"])?.stdout;

   // Then you can happily use the output
}
```

## Logging

Debug logging in starship is done with our custom logger implementation.
To run starship with debug logs, set the `STARSHIP_LOG` environment variable to the log level needed.
For example, to enable the trace logs, run the following:

```sh
# Run installed starship
STARSHIP_LOG=trace starship

# Run with cargo
STARSHIP_LOG=trace cargo run
```

## Linting

Starship source files are linted with [clippy](https://crates.io/crates/clippy). Clippy will be ran as part of CI. Linting errors will fail a build, so it is suggested that you run Clippy locally:

```sh
rustup component add clippy
cargo clippy --all-targets --all-features
```

## Formatting

Starship source files are formatted with [rustfmt](https://crates.io/crates/rustfmt-nightly), using the default configuration. Rustfmt will be ran as part of CI. Unformatted code will fail a build, so it is suggested that you run rustfmt locally:

```sh
rustup component add rustfmt
cargo fmt
```

## Testing

Testing is critical to making sure starship works as intended on systems big and small. Starship interfaces with many applications and system APIs when generating the prompt, so there's a lot of room for bugs to slip in.

Unit tests are written using the built-in Rust testing library in the same file as the implementation, as is traditionally done in Rust codebases. These tests can be run with `cargo test` and are run on GitHub as part of our GitHub Actions continuous integration to ensure consistent behavior.

All tests that test the rendered output of a module should use `ModuleRenderer`. For Example:

```rust
use super::{Context, Module, RootModuleConfig};

use crate::configs::php::PhpConfig;
use crate::formatter::StringFormatter;
use crate::utils;


pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
   /* This is where your module code goes */
}

#[cfg(test)]
mod tests {
   use super::*;
   use crate::test::ModuleRenderer;
   use ansi_term::Color;
   use std::fs::File;
   use std::io;


   #[test]
   fn should_render() -> io::Result<()> {
      // Here you setup the testing environment
      let tempdir = tempfile::tempdir()?;
      // Create some file needed to render the module
      File::create(dir.path().join("YOUR_FILE"))?.sync_all()?;

      // The output of the module
      let actual = ModuleRenderer::new("YOUR_MODULE_NAME")
         // For a custom path
         .path(&tempdir.path())
         // For a custom config
         .config(toml::toml!{
            [YOUR_MODULE_NAME]
            val = 1
         })
         // For env mocking
         .env("KEY","VALUE")
         // Run the module and collect the output
         .collect();

      // The value that should be rendered by the module.
      let expected = Some(format!("{} ",Color::Black.paint("THIS SHOULD BE RENDERED")));

      // Assert that the actual and expected values are the same
      assert_eq!(actual, expected);

      // Close the tempdir
      tempdir.close()
   }
}
```

If a module depends on output of another program, then that output should be added to the match statement in [`utils.rs`](src/utils.rs). The match has to be exactly the same as the call to `utils::exec_cmd()`, including positional arguments and flags. The array of arguments are joined by a `" "`, so `utils::exec_cmd("program", &["arg", "more_args"])` would match with the `program arg more_args` match statement.

If the program cannot be mocked (e.g. It performs some filesystem operations, either writing or reading files) then it has to added to the project's GitHub Actions workflow file([`.github/workflows/workflow.yml`](.github/workflows/workflow.yml)) and the test has to be marked with an `#[ignored]`. This ensures that anyone can run the test suite locally without needing to pre-configure their environment. The `#[ignored]` attribute is bypassed during CI runs in GitHub Actions.

Unit tests should be fully isolated, only testing a given function's expected output given a specific input, and should be reproducible on any machine. Unit tests should not expect the computer running them to be in any particular state. This includes having any applications pre-installed, having any environment variables set, etc.

The previous point should be emphasized: even seemingly innocuous ideas like "if we can see the directory, we can read it" or "nobody will have their home directory be a git repo" have bitten us in the past. Having even a single test fail can completely break installation on some platforms, so be careful with tests!

### Test Programming Guidelines

Any tests that depend on File I/O should use [`sync_all()`](https://doc.rust-lang.org/std/fs/struct.File.html#method.sync_all) when creating files or after writing to files.

Any tests that use `tempfile::tempdir` should take care to call `dir.close()` after usage to ensure the lifecycle of the directory can be reasoned about. This includes `fixture_repo()` as it returns a TempDir that should be closed.

## Running the Documentation Website Locally

If you are contributing to the design of Starship's website, the following section will help you get started.

### Setup

After cloning the project, you can do the following to run the VuePress website on your local machine:

1. `cd` into the `/docs` directory.
2. Install the project dependencies:

   ```sh
   npm install
   ```

3. Start the project in development mode:

   ```sh
   npm run dev
   ```

Once setup is complete, you can refer to VuePress documentation on the actual implementation here: <https://vuepress.vuejs.org/guide/>.

## Git/GitHub workflow

This is our preferred process for opening a PR on GitHub:

1. Fork this repository
2. Create a branch off of `master` for your work: `git checkout -b my-feature-branch`
3. Make some changes, committing them along the way
4. When your changes are ready for review, push your branch: `git push origin my-feature-branch`
5. Create a pull request from your branch to `starship/master`
6. No need to assign the pull request to anyone, we'll review it when we can
7. When the changes have been reviewed and approved, someone will squash and merge for you