# Contributing Guidelines There are two main ways to contribute to the project — submitting issues and submitting fixes/changes/improvements via pull requests. ## Submitting issues Both bug reports and feature requests are welcome. Submit issues [here](https://github.com/Kotlin/kotlinx.coroutines/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 already fixed. * By default, we assume that your problem reproduces in Kotlin/JVM. Please, mention if the problem is specific to Kotlin/JS or Kotlin/Native. * Include the code that reproduces the problem. Provide the complete reproducer code, yet minimize it as much as possible. * However, don't put off reporting any weird or rarely appearing issues just because you cannot consistently reproduce them. * If the bug is in behavior, then explain what behavior you've expected and what you've got. * When submitting a feature request: * Explain why you need the feature — what's your use-case, what's your domain. * Explaining the problem you face is more important than suggesting a solution. Report your problem even if you don't have any proposed solution. * If there is an alternative way to do what you need, then show the code of the alternative. ## Submitting PRs We love PRs. Submit PRs [here](https://github.com/Kotlin/kotlinx.coroutines/pulls). However, please keep in mind that maintainers will have to support the resulting code of the project, so do familiarize yourself with the following guidelines. * All development (both new features and bug fixes) is performed in the `develop` branch. * The `master` branch always contains sources of the most recently released version. * Base PRs against the `develop` branch. * The `develop` branch is pushed to the `master` branch during release. * Documentation in markdown files can be updated directly in the `master` branch, unless the documentation is in the source code, and the patch changes line numbers. * If you fix documentation: * After fixing/changing code examples in the [`docs`](docs) folder or updating any references in the markdown files run the [Knit tool](#running-the-knit-tool) and commit the resulting changes as well. It will not pass the tests otherwise. * If you plan extensive rewrites/additions to the docs, then please [contact the maintainers](#contacting-maintainers) to coordinate the work in advance. * If you make any code changes: * Follow the [Kotlin Coding Conventions](https://kotlinlang.org/docs/reference/coding-conventions.html). Use 4 spaces for indentation. * [Build the project](#building) to make sure it all works and passes the tests. * If you fix a bug: * Write the test that reproduces the bug. * Fixes without tests are accepted only in exceptional circumstances if it can be shown that writing the corresponding test is too hard or otherwise impractical. * Follow the style of writing tests that is used in this project: name test functions as `testXxx`. Don't use backticks in test names. * If you introduce any new public APIs: * Comment on the existing issue if you want to work on it or create one beforehand. Ensure that the issue not only describes a problem, but also describes a solution that had received a positive feedback. Propose a solution if there isn't any. PRs with new API, but without a corresponding issue with a positive feedback about the proposed implementation are unlikely to be approved or reviewed. * All new APIs must come with documentation and tests. * All new APIs are initially released with `@ExperimentalCoroutineApi` annotation and are graduated later. * [Update the public API dumps](#updating-the-public-api-dump) and commit the resulting changes as well. It will not pass the tests otherwise. * If you plan large API additions, then please start by submitting an issue with the proposed API design to gather community feedback. * [Contact the maintainers](#contacting-maintainers) to coordinate any big piece of work in advance. * Steps for contributing new integration modules are explained [here](integration/README.md#Contributing). ## Building This library is built with Gradle. * Run `./gradlew build` to build. It also runs all the tests. * Run `./gradlew :test` to test the module you are looking at to speed things up during development. * Run `./gradlew jvmTest` to perform only fast JVM tests of the core multiplatform module. You can import this project into IDEA, but you have to delegate build actions to Gradle (in Preferences -> Build, Execution, Deployment -> Build Tools -> Gradle -> Runner) ### Environment requirements * JDK >= 11 referred to by the `JAVA_HOME` environment variable. * JDK 1.8 referred to by the `JDK_18` environment variable. Only used by nightly stress-tests. It is OK to have `JDK_18` to a non 1.8 JDK (e.g. `JAVA_HOME`) for external contributions. For external contributions you can for example add this to your shell startup scripts (e.g. `~/.zshrc`): ```shell # This assumes JAVA_HOME is set already to a JDK >= 11 version export JDK_18="$JAVA_HOME" ``` ### Running the Knit tool * Use [Knit](https://github.com/Kotlin/kotlinx-knit/blob/main/README.md) for updates to documentation: * Run `./gradlew knit` to update example files, links, tables of content. * Commit updated documents and examples together with other changes. ### Updating the public API dump * Use [Binary Compatibility Validator](https://github.com/Kotlin/binary-compatibility-validator/blob/master/README.md) for updates to public API: * Run `./gradlew apiDump` to update API index files. * Commit updated API indexes together with other changes. ## Releases * Full release procedure checklist is [here](RELEASE.md). ## Contacting maintainers * If something cannot be done, not convenient, or does not work — submit an [issue](#submitting-issues). * "How to do something" questions — [StackOverflow](https://stackoverflow.com). * Discussions and general inquiries — use `#coroutines` channel in [KotlinLang Slack](https://kotl.in/slack).