# Contributing Guidelines

There are three main ways you can contribute to Dokka's development:

* Submitting issues.
* Submitting fixes/changes/improvements via pull requests.
* Developing community plugins.

## Submitting issues

Bug reports, feature requests and questions are welcome. Submit issues [here](https://github.com/Kotlin/dokka/issues).

* Search for existing issues to avoid reporting duplicates.
* When submitting a bug report:
   * Test it against the most recently released version. It might have been fixed already.
   * Include code that reproduces the problem. Provide a complete reproducer, yet minimize it as much as 
     possible. A separate project that can be cloned is ideal.
   * If the bug is in behavior, explain what behavior you expected and what the actual result is.
* When submitting a feature request:
   * Explain why you need the feature.
   * Explaining the problem you face is more important than suggesting a solution.
     Report your problem even if you have no proposed solution.

## Submitting PRs

Dokka has extensive [Developer Guides](https://kotlin.github.io/dokka/1.9.0/developer_guide/introduction/) documentation
which goes over the development [Workflow](https://kotlin.github.io/dokka/1.9.0/developer_guide/workflow/) and 
[Dokka's architecture](https://kotlin.github.io/dokka/1.9.0/developer_guide/architecture/architecture_overview/),
which can help you understand how to achieve what you want and where to look.

All development (both new features and bugfixes) takes place in the `master` branch, it contains sources for the next
version of Dokka.

For any code changes:

* Follow [Kotlin Coding Conventions](https://kotlinlang.org/docs/reference/coding-conventions.html).
  Use 4 spaces for indentation.
* [Build the project](#build-dokka-locally) to make sure it all works and tests pass.
* Write tests that reproduce the bug or test new features.
* PRs without tests are accepted only in exceptional circumstances if it is evident that writing the
  corresponding test is too hard or otherwise impractical.
* If you add new or change old public API, [update public API dump](#updating-public-api-dump), otherwise it will fail 
  the build.

Please [contact maintainers](#contacting-maintainers) in advance to coordinate any big piece of work.

## Working with the code

### Build Dokka locally

Building Dokka is pretty straightforward, with one small caveat: when you run `./gradlew build`, it will run integration
tests as well, which might take some time and will consume a lot of RAM (~20-30 GB), so you would usually want to exclude 
integration tests when building locally:

```Bash
./gradlew build -x integrationTest
```

Unit tests which are run as part of `build` should not take much time, but you can also skip it with `-x test`.

### Use/test locally built Dokka

Below you will find a bare-bones instruction on how to use and test locally built Dokka. For more details and examples, 
visit [Workflow](https://kotlin.github.io/dokka/1.9.0/developer_guide/workflow/) topic.

1. Change `dokka_version` in `gradle.properties` to something that you will use later on as the dependency version.
   For instance, you can set it to something like `1.9.0-my-fix-SNAPSHOT`.
2. Publish it to Maven Local (`./gradlew publishToMavenLocal`)
3. In the project for which you want to generate documentation add Maven Local as a buildscript/dependency
   repository (`mavenLocal()`)
4. Update your Dokka dependency to the version you've just published:

```kotlin
plugins {
    id("org.jetbrains.dokka") version "1.9.0-my-fix-SNAPSHOT"
}
```

### Updating public API dump

[Binary Compatibility Validator](https://github.com/Kotlin/binary-compatibility-validator/blob/master/README.md) 
is used to keep track of public API changes.

Run `./gradlew apiDump` to update API index files after introducing new or changing old public API. Commit updated 
API indexes together with other changes.

## Infrastructure

### Java version

To minimize compatibility problems, [Gradle's Java toolchains](https://docs.gradle.org/current/userguide/toolchains.html)
are [used](build-logic/src/main/kotlin/org/jetbrains/conventions/base-java.gradle.kts) to build and test the project.

When run, Gradle tries to auto-detect the required JRE/JDK installation locally, but it may fail if you don't have
that version of Java installed or if it's installed in an unusual location. Please refer to 
[Gradle's documentation on toolchains](https://docs.gradle.org/current/userguide/toolchains.html#sec:auto_detection)
for customization and problem resolution questions.

You can use the following [Gradle properties](gradle.properties) to build/test
Dokka with a different version of Java:

| Property                                         | Default value | Description                                      |
|--------------------------------------------------|---------------|--------------------------------------------------|
| `org.jetbrains.dokka.javaToolchain.mainCompiler` | `8`           | The version used to build Dokka projects.        |
| `org.jetbrains.dokka.javaToolchain.testLauncher` | `8`           | The version used run unit and integration tests. |

Separating the compiler and test versions is needed to check Dokka's compatibility with various Java versions.
For example, the GitHub Actions based unit tests are 
[run under multiple versions of Java](.github/workflows/tests-thorough.yml)
at the same time.

### GitHub Actions

The majority of automated checks and builds are run as 
[GitHub Actions workflows](https://docs.github.com/en/actions/using-workflows/about-workflows).

The configuration for Dokka's workflows can be found in [`.github/workflows`](.github/workflows). 

For your first PR, a maintainer will need to approve the workflow runs manually. For your subsequent PRs, the workflows
will be triggered and run automatically on every PR commit.

While GitHub Actions checks can expose real problems, [TeamCity-based integration tests](#teamcity) need to be run for 
any significant changes as they have more thorough compatibility checks. 

Notable workflows:

* [Publish preview to GitHub Actions Artifacts](https://github.com/Kotlin/dokka/actions/workflows/preview-publish-ga.yml)
  builds the HTML API reference of several libraries like `kotlinx.coroutines`, and publishes the results as `zip` archive 
  artifacts. You can use it to preview your changes. The workflow is triggered for all commits.
* [Publish preview to web (S3)](https://github.com/Kotlin/dokka/actions/workflows/preview-publish-web-s3.yml)
  does the same thing as `Publish examples to GitHub Actions Artifacts`, but publishes the generated documentation
  to S3, so it can be accessed from any browser without the need to download anything. The web link will be printed
  under the `Print link` job step. This workflow is triggered by maintainer commits only as it requires encrypted 
  secrets to be run.

**Notes**:

* Some workflow job runs are flaky, but if more than a couple are failing at the same time or repeatedly - it indicates 
  a problem in the PR that needs to be addressed.
* While a Java version can be configured in the [`setup-java`](https://github.com/actions/setup-java#basic-configuration)
  action, it is not necessarily the version of Java that will be used to build/test the project. See the 
  [Java version](#java-version) section for more details.

### TeamCity

TeamCity is used for a subset of important / longer builds and checks, including artifact publication. 

The runs are triggered automatically by maintainer commits, or can be started manually by maintainers. External 
contributors can view the results in guest mode.

Notable builds:

* [Dokka Integration Tests](https://teamcity.jetbrains.com/buildConfiguration/KotlinTools_Dokka_IntegrationTests)
  runs Dokka's integration tests, which are designed to test compatibility with different Kotlin versions, with different
  multiplatform targets and with various user scenarios.

## Contacting maintainers

* If something cannot be done, not convenient, or does not work — submit an [issue](#submitting-issues).
* Discussions and general inquiries — use `#dokka` channel in 
  [Kotlin Community Slack](https://surveys.jetbrains.com/s3/kotlin-slack-sign-up).