copier/CONTRIBUTING.md

# Contributing

Contributions are welcome, and they are greatly appreciated! Every little bit helps, and
credit will always be given.

## Report Bugs

Report bugs at <https://github.com/copier-org/copier/issues>.

If you are reporting a bug, please include:

-   Your operating system name and version.
-   Any details about your local setup that might be helpful in troubleshooting.
-   Detailed steps to reproduce the bug.

## Fix Bugs

Look through the GitHub issues for bugs. Anything tagged with "bug" is open to whoever
wants to implement it.

## Implement Features

Look through the GitHub issues for features. Anything tagged with "Feature request" is
open to whoever wants to implement it.

## Write Documentation

The project could always use more documentation, whether as part of the official project
docs, or even on the web in blog posts, articles, and such.

## Submit Feedback

The best way to send feedback is to file an issue at
<https://github.com/copier-org/copier/issues>.

If you are proposing a feature:

-   Explain in detail how it would work.
-   Keep the scope as narrow as possible, to make it easier to implement.
-   Remember that this is a volunteer-driven project, and that contributions are
    welcome. :)

## Discuss

Feel free to discuss with our community through
[our discussions channel](https://github.com/copier-org/copier/discussions). Be polite!

## Dev Environment Setup

The recommended way is:

1. Click on
   [![Gitpod ready-to-code](https://img.shields.io/badge/Gitpod-ready--to--code-blue?logo=gitpod)](https://gitpod.io/#https://github.com/copier-org/copier)
1. Wait until the terminal that pops up is ready.
1. Accept the direnv and nix pop-ups that appear.

For local or more complex setups, continue reading.

We use some tools as part of our development workflow which you'll need to install into
your host environment:

-   [Nix](https://nixos.org/download.html) to provide a reproducible development
    environment.
-   [Direnv](https://direnv.net/) to load that environment automatically in your shell.

### Without Nix

For some reasons you might want to avoid installing Nix in your system. Maybe you don't
have enough permissions, you work on Windows, or you just don't want to add yet another
package manager to your system. We believe Nix is awesome enough so as to be the default
tool for almost any developer, but we respect your choice.

You can use standard Python tooling such as [uv][] and a valid Python installation
installed in an imperative manner of your choice, e.g. using uv as well.

However, you won't be able to auto-lint or auto-format code without Nix. If you don't
have Nix installed but you have Docker or Podman, you can run `poe lint` and get similar
results. It will use a container to install Nix, and Nix to install the formatters.

If you still don't have Docker or Podman, don't worry. You can push your changes without
formatting. As long as you give Copier maintainers permissions to change your PR, a bot
will kindly auto-format code for you and push it back to your branch.

[uv]: https://docs.astral.sh/uv/

## Get Started!

Ready to contribute? Here's how to set up the project for local development.

1.  Fork the Copier repo on GitHub.
1.  Clone your fork locally:

    ```shell
    git clone git@github.com:my-user/copier.git
    cd copier
    ```

1.  Use Direnv to set up a development environment:

    ```shell
    # Let direnv do its magic
    direnv allow
    ```

    Direnv will take some time to load for the 1st time. It will download all
    development dependencies, including [uv][], and it will use it to create a
    virtualenv and install Copier with all its development dependencies too.

1.  Create a branch for local development:

    ```shell
    git checkout -b name-of-your-bugfix-or-feature
    ```

    Now you can make your changes locally.

1.  When you're done making changes, check that your changes pass all tests:

    ```shell
    uv run poe test
    uv run poe lint
    ```

1.  Optionally, use pyclean to remove Python bytecode and build artifacts, e.g.

    ```shell
    uvx pyclean . --debris --verbose
    ```

    or

    ```shell
    pipx run pyclean . --debris --verbose
    ```

1.  Commit your changes and push your branch to GitHub:

    ```shell
    git add .
    cz commit  # use `git commit` if you prefer, but this helps
    git push origin name-of-your-bugfix-or-feature
    ```

1.  Submit a pull request through the GitHub website.

## Pull Request Guidelines

Before you submit a pull request, check that it meets these guidelines:

1.  The pull request has code, it should include tests.
1.  Check that all checks pass on GitHub CI.
1.  If something significant changed, modify docs.

### Commit message guidelines

Follow [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/) standard.

We use [Commitizen](https://commitizen-tools.github.io/commitizen/) to handle Copier
releases. This tool generates the appropriate tag based on that standard. It also writes
our [changelog](CHANGELOG.md). Changes that are included there are of type `fix`, `feat`
and `refactor`; also `BREAKING CHANGE:` trailers will appear. If your change is not
meaningful in the changelog, then please don't use one of those categories.

### Maintainer notes

If you're a maintainer and you want to merge a PR that will produce a confusing
changelog, then please squash the PR on merge, and change the commit message to make it
meaningful. Remember to
[respect co-autorship](https://docs.github.com/en/pull-requests/committing-changes-to-your-project/creating-and-editing-commits/creating-a-commit-with-multiple-authors)
when squashing, especially if multiple authors were involved.

If the last commit is pushed back by `github-actions[bot]` and named
`style: autoformat with pre-commit`, it's most likely an automatic reformatting commit
done by the CI.
[Those kind of commits cannot trigger other workflows](https://docs.github.com/en/actions/using-workflows/triggering-a-workflow#triggering-a-workflow-from-a-workflow).
Thus, to be able to re-run CI, close and reopen the PR. Consider squashing on merge if
possible and practical.

## Tips

To run a subset of tests:

```shell
uv run poe test tests/the-tests-file.py
```

## Nix binary cache

Our direnv configuration is configured to use binary caches by default.

However, to add our binary caches permanently:

```shell
nix-shell -p cachix --run 'cachix use copier && cachix use devenv'
```

If you use Nix Flakes, add `--accept-flake-config` to install our binary cache
automatically.

## How to create a new release

This section is for maintainers. Since we use the
[conventional commits](https://www.conventionalcommits.org/) standard, the easiest way
to create a new release is to open Copier repo locally and run:

```shell
# Make sure you're in the last commit
git checkout master
git pull --tags

# Create a new changelog entry and bump the version automatically
cz bump --retry

# Push it
git push --tags
```

Now the tag is released, but GitHub won't display it in the releases page. For that:

1. [Draft a new release](https://github.com/copier-org/copier/releases/new).
1. Choose the tag you just pushed.
1. Set the tag also as release title.
1. Copy the just added changelog entry from [CHANGELOG](./CHANGELOG.md) and paste it as
   a description.
1. Enable "Set as the latest release".
1. Optionally, enable "Create a discussion for this release".
1. Click on "Publish release".