# Contributing

Contribution to diff-lcs is encouraged: bug reports, feature requests, or code
contributions. New features should be proposed and discussed in an
[issue][issues].

Before contributing patches, please read the [Licence](./LICENCE.md).

diff-lcs is governed under the [Contributor Covenant Code of Conduct][cccoc].

## Code Guidelines

I have several guidelines to contributing code through pull requests:

- All code changes require tests. In most cases, this will be added or updated
  unit tests. I use [Minitest][minitest].

  - There are integration tests with RSpec which must not be broken, accessible
    through `rake integration`. This requires a non-bundled RSpec,
    `gem install rspec`.

- I use code formatters, static analysis tools, and linting to ensure consistent
  styles and formatting. There should be no warning output from test run
  processes. I use [Standard Ruby][standardrb].

- Proposed changes should be on a thoughtfully-named topic branch and organized
  into logical commit chunks as appropriate.

- Use [Conventional Commits][conventional] with my
  [conventions](#commit-conventions).

- Versions must not be updated in pull requests unless otherwise directed. This
  means that you must not:

  - Modify `VERSION` in `lib/diff/lcs/version.rb`. When your patch is accepted
    and a release is made, the version will be updated at that point.

  - Modify `diff-lcs.gemspec`; it is a generated file. (You _may_ use
    `rake gemspec` to regenerate it if your change involves metadata related to
    gem itself).

  - Modify the `Gemfile`.

- Documentation should be added or updated as appropriate for new or updated
  functionality. The documentation is RDoc; diff-lcs does not use extensions
  that may be present in alternative documentation generators.

- All GitHub Actions checks marked as required must pass before a pull request
  may be accepted and merged.

- Add your name or GitHub handle to `CONTRIBUTORS.md` and a record in the
  `CHANGELOG.md` as a separate commit from your main change. (Follow the style
  in the `CHANGELOG.md` and provide a link to your PR.)

- Include your DCO sign-off in each commit message (see [LICENCE](LICENCE.md)).

## AI Contribution Policy

diff-lcs is a library with complex interactions and subtle decisions (some of
them possibly even wrong). It is extremely important that contributions of any
sort be well understood by the submitter and that the developer can attest to
the [Developer Certificate of Origin][dco] for each pull request (see
[LICENCE](LICENCE.md)).

Any contribution (bug, feature request, or pull request) that uses undeclared AI
output will be rejected.

## Test Dependencies

diff-lcs uses Ryan Davis's [Hoe][Hoe] to manage the release process, and it adds
a number of rake tasks. You will mostly be interested in `rake`, which runs
tests in the same way that `rake spec` does.

To assist with the installation of the development dependencies for diff-lcs, I
have provided a Gemfile pointing to the (generated) `diff-lcs.gemspec` file.
This will permit you to use `bundle install` to install the dependencies.

You can run tests with code coverage analysis by running `rake spec:coverage`.

## Commit Conventions

diff-lcs has adopted a variation of the Conventional Commits format for commit
messages. The following types are permitted:

| Type    | Purpose                                               |
| ------- | ----------------------------------------------------- |
| `feat`  | A new feature                                         |
| `fix`   | A bug fix                                             |
| `chore` | A code change that is neither a bug fix nor a feature |
| `docs`  | Documentation updates                                 |
| `deps`  | Dependency updates, including GitHub Actions.         |

I encourage the use of [Tim Pope's][tpope-qcm] or [Chris Beam's][cbeams]
guidelines on the writing of commit messages

I require the use of [git][trailers1] [trailers][trailers2] for specific
additional metadata and strongly encourage it for others. The conditionally
required metadata trailers are:

- `Breaking-Change`: if the change is a breaking change. **Do not** use the
  shorthand form (`feat!(scope)`) or `BREAKING CHANGE`.

- `Signed-off-by`: this is required for all developers except me, as outlined in
  the [Licence](./LICENCE.md#developer-certificate-of-origin).

- `Fixes` or `Resolves`: If a change fixes one or more open [issues][issues],
  that issue must be included in the `Fixes` or `Resolves` trailer. Multiple
  issues should be listed comma separated in the same trailer:
  `Fixes: #1, #5, #7`, but _may_ appear in separate trailers. While both `Fixes`
  and `Resolves` are synonyms, only _one_ should be used in a given commit or
  pull request.

- `Related to`: If a change does not fix an issue, those issue references should
  be included in this trailer.

[cbeams]: https://cbea.ms/git-commit/
[cccoc]: ./CODE_OF_CONDUCT.md
[conventional]: https://www.conventionalcommits.org/en/v1.0.0/
[dco]: licences/dco.txt
[hoe]: https://github.com/seattlerb/hoe
[issues]: https://github.com/halostatue/diff-lcs/issues
[minitest]: https://github.com/seattlerb/minitest
[rspec]: https://rspec.info/documentation/
[standardrb]: https://github.com/standardrb/standard
[tpope-qcm]: https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
[trailers1]: https://git-scm.com/docs/git-interpret-trailers
[trailers2]: https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---trailerlttokengtltvaluegt
