# Contributing

## Building

Install Rust with rustup, then clone the code.

    $ git clone git@github.com:Wilfred/difftastic.git
    $ cd difftastic

Difftastic uses Cargo for building.

    $ cargo build

Debug builds are significantly slower than release builds. For files with more than fifty lines, it's usually worth using an optimised build.

    $ cargo build --release

## Manual

This website is generated with mdbook. mdbook can be installed with Cargo.

    $ cargo install mdbook

You can then use the `mdbook` binary to build and serve the site locally.

    $ cd manual
    $ mdbook serve

## API Documentation

You can browse the internal API documentation generated by rustdoc here.

Difftastic's internal docs are not available on docs.rs, as it does not support binary crates today.

## Testing

    $ cargo test

There are also several files in `sample_files/` that you can use.

The best way to test difftastic is to look at history from a real project. Set `GIT_EXTERNAL_DIFF` to point to your current build.

For example, you can run difftastic on its own source code.

    $ GIT_EXTERNAL_DIFF=./target/release/difft git log -p --ext-diff -- src

## Logging

Difftastic uses the `pretty_env_logger` library to log some additional debug information.

    $ DFT_LOG=debug cargo run sample_files/old.jsx sample_files/new.jsx

See the `env_logger` documentation for full details.

## Releasing

Use Cargo to create a new release, and tag it in git. Difftastic has a helper script for this:

    $ ./scripts/release.sh

You can now increment the version in Cargo.toml and add a new entry to CHANGELOG.md.