# Contributing

Thank you for your interest in go-toml! We appreciate you considering

contributing to go-toml!

The main goal is the project is to provide an easy-to-use and efficient TOML

implementation for Go that gets the job done and gets out of your way – dealing

with TOML is probably not the central piece of your project.

As the single maintainer of go-toml, time is scarce. All help, big or small, is

more than welcomed!

## Ask questions

Any question you may have, somebody else might have it too. Always feel free to

ask them on the [discussion board][discussions]. We will try to answer them as

clearly and quickly as possible, time permitting.

Asking questions also helps us identify areas where the documentation needs

improvement, or new features that weren't envisioned before. Sometimes, a

seemingly innocent question leads to the fix of a bug. Don't hesitate and ask

away!

[discussions]: https://github.com/pelletier/go-toml/discussions

## Improve the documentation

The best way to share your knowledge and experience with go-toml is to improve

the documentation. Fix a typo, clarify an interface, add an example, anything

goes!

The documentation is present in the [README][readme] and thorough the source

code. On release, it gets updated on [pkg.go.dev][pkg.go.dev]. To make a change

to the documentation, create a pull request with your proposed changes. For

simple changes like that, the easiest way to go is probably the "Fork this

project and edit the file" button on Github, displayed at the top right of the

file. Unless it's a trivial change (for example a typo), provide a little bit of

context in your pull request description or commit message.

## Report a bug

Found a bug! Sorry to hear that :(. Help us and other track them down and fix by

reporting it. [File a new bug report][bug-report] on the [issues

tracker][issues-tracker]. The template should provide enough guidance on what to

include. When in doubt: add more details! By reducing ambiguity and providing

more information, it decreases back and forth and saves everyone time.

## Code changes

Want to contribute a patch? Very happy to hear that!

First, some high-level rules:

- A short proposal with some POC code is better than a lengthy piece of text

  with no code. Code speaks louder than words. That being said, bigger changes

  should probably start with a [discussion][discussions].

- No backward-incompatible patch will be accepted unless discussed. Sometimes

  it's hard, but we try not to break people's programs unless we absolutely have

  to.

- If you are writing a new feature or extending an existing one, make sure to

  write some documentation.

- Bug fixes need to be accompanied with regression tests.

- New code needs to be tested.

- Your commit messages need to explain why the change is needed, even if already

  included in the PR description.

It does sound like a lot, but those best practices are here to save time overall

and continuously improve the quality of the project, which is something everyone

benefits from.

### Get started

The fairly standard code contribution process looks like that:

1. [Fork the project][fork].

2. Make your changes, commit on any branch you like.

3. [Open up a pull request][pull-request]

4. Review, potential ask for changes.

5. Merge.

Feel free to ask for help! You can create draft pull requests to gather

some early feedback!

### Run the tests

You can run tests for go-toml using Go's test tool: `go test -race ./...`.

During the pull request process, all tests will be ran on Linux, Windows, and

MacOS on the last two versions of Go.

However, given GitHub's new policy to _not_ run Actions on pull requests until a

maintainer clicks on button, it is highly recommended that you run them locally

as you make changes.

### Check coverage

We use `go tool cover` to compute test coverage. Most code editors have a way to

run and display code coverage, but at the end of the day, we do this:

```

go test -covermode=atomic -coverprofile=coverage.out

go tool cover -func=coverage.out

```

and verify that the overall percentage of tested code does not go down. This is

a requirement. As a rule of thumb, all lines of code touched by your changes

should be covered. On Unix you can use `./ci.sh coverage -d v2` to check if your

code lowers the coverage.

### Verify performance

Go-toml aims to stay efficient. We rely on a set of scenarios executed with Go's

builtin benchmark systems. Because of their noisy nature, containers provided by

Github Actions cannot be reliably used for benchmarking. As a result, you are

responsible for checking that your changes do not incur a performance penalty.

You can run their following to execute benchmarks:

```

go test ./... -bench=. -count=10

```

Benchmark results should be compared against each other with

[benchstat][benchstat]. Typical flow looks like this:

1. On the `v2` branch, run `go test ./... -bench=. -count 10` and save output to

   a file (for example `old.txt`).

2. Make some code changes.

3. Run `go test ....` again, and save the output to an other file (for example

   `new.txt`).

4. Run `benchstat old.txt new.txt` to check that time/op does not go up in any

   test.

On Unix you can use `./ci.sh benchmark -d v2` to verify how your code impacts

performance.

It is highly encouraged to add the benchstat results to your pull request

description. Pull requests that lower performance will receive more scrutiny.

[benchstat]: https://pkg.go.dev/golang.org/x/perf/cmd/benchstat

### Style

Try to look around and follow the same format and structure as the rest of the

code. We enforce using `go fmt` on the whole code base.

---

## Maintainers-only

### Merge pull request

Checklist:

- Passing CI.

- Does not introduce backward-incompatible changes (unless discussed).

- Has relevant doc changes.

- Benchstat does not show performance regression.

- Pull request is [labeled appropriately][pr-labels].

- Title will be understandable in the changelog.

1. Merge using "squash and merge".

2. Make sure to edit the commit message to keep all the useful information

   nice and clean.

3. Make sure the commit title is clear and contains the PR number (#123).

### New release

1. Decide on the next version number. Use semver.

2. Generate release notes using [`gh`][gh]. Example:

```

$ gh api -X POST \

  -F tag_name='v2.0.0-beta.5' \

  -F target_commitish='v2' \

  -F previous_tag_name='v2.0.0-beta.4' \

  --jq '.body' \

  repos/pelletier/go-toml/releases/generate-notes

```

3. Look for "Other changes". That would indicate a pull request not labeled

   properly. Tweak labels and pull request titles until changelog looks good for

   users.

4. [Draft new release][new-release].

5. Fill tag and target with the same value used to generate the changelog.

6. Set title to the new tag value.

7. Paste the generated changelog.

8. Check "create discussion", in the "Releases" category.

9. Check pre-release if new version is an alpha or beta.

[issues-tracker]: https://github.com/pelletier/go-toml/issues

[bug-report]: https://github.com/pelletier/go-toml/issues/new?template=bug_report.md

[pkg.go.dev]: https://pkg.go.dev/github.com/pelletier/go-toml

[readme]: ./README.md

[fork]: https://help.github.com/articles/fork-a-repo

[pull-request]: https://help.github.com/en/articles/creating-a-pull-request

[new-release]: https://github.com/pelletier/go-toml/releases/new

[gh]: https://github.com/cli/cli

[pr-labels]: https://github.com/pelletier/go-toml/blob/v2/.github/release.yml