Contributing to Flutter Plugins

Build Status

See also: Flutter's code of conduct

Important note

As of January 2021, we are no longer accepting non-critical PRs for plugins for which there is a corresponding Flutter Community Plus Plugin, as we hope in time to be able to transition users to those versions of the plugins. If you have a PR for something other than a critical issue (crashes, build failures, null safety, etc.) for any of the following plugins, we encourage you to submit it there instead:

  • android_alarm_manager
  • android_intent
  • battery
  • connectivity
  • device_info
  • package_info
  • sensors
  • share
  • wifi_info_flutter (corresponds to network_info_plus)

Things you will need

  • Linux, Mac OS X, or Windows.
  • git (used for source version control).
  • An ssh client (used to authenticate with GitHub).

Getting the code and configuring your environment

  • Ensure all the dependencies described in the previous section are installed.
  • Fork https://github.com/flutter/plugins into your own GitHub account. If you already have a fork, and are now installing a development environment on a new machine, make sure you‘ve updated your fork so that you don’t use stale configuration options from long ago.
  • If you haven‘t configured your machine with an SSH key that’s known to github, then follow GitHub's directions to generate an SSH key.
  • git clone git@github.com:<your_name_here>/plugins.git
  • cd plugins
  • git remote add upstream git@github.com:flutter/plugins.git (So that you fetch from the master repository, not your clone, when running git fetch et al.)

Running the examples

To run an example with a prebuilt binary from the cloud, switch to that example's directory, run pub get to make sure its dependencies have been downloaded, and use flutter run. Make sure you have a device connected over USB and debugging enabled on that device.

  • cd packages/battery/example
  • flutter run

Setting up XCUITests

Sometimes, XCUITests are useful when integration testing a plugin that has native UI on iOS (e.g image_picker, in_app_purchase, camera, share, local_auth etc). Most of the time, XCUITests are not necessary, consider using integration_test if the tests are not focused on iOS system UI.

If XCUITests has always been set up for the plugin, a RunnerUITests folder under <the_plugin>/example/ios directory can be found. If XCUITests has not been set up for the plugin, follow these steps to set it up:

  1. Open <path_to_plugin>/example/ios/Runner.xcworkspace using XCode.
  2. Create a new “UI Testing Bundle”.
  3. In the target options window, populate details as following, then click on “Finish”.
  • In the “product name” field, type in “RunnerUITests” (this is the test target name our CI looks for.).
  • In the “Team” field, select “None”.
  • In the Organization Name field, type in “Flutter”. This should usually be pre-populated.
  • In the organization identifer field, type in “com.google”. This should usually be pre-populated.
  • In the Language field, select “Objective-C”.
  • In the Project field, select the xcodeproj “Runner” (blue color).
  • In the Target to be Tested, select xcworkspace “Runner” (white color).
  1. A RunnerUITests folder should be created and you can start hacking in RunnerUITests.m.
  2. To enable the test on CI, the plugin needs to be removed from the “skip” list:
  • Open ./cirrus.yml and find PLUGINS_TO_SKIP_XCTESTS.
  • Remove the plugin name from the list.

Running the tests

Integration tests

To run the integration tests using Flutter driver:

cd example
flutter drive test_driver/<name_of_plugin_test>.dart

To run integration tests as instrumentation tests on a local Android device:

cd example
flutter build apk
cd android && ./gradlew -Ptarget=$(pwd)/../test_driver/<name_of_plugin>_test.dart app:connectedAndroidTest

These tests may also be in folders just named “test,” or have filenames ending with “e2e”.

Dart unit tests

To run the unit tests:

flutter test test/<name_of_plugin>_test.dart

Java unit tests

These can be ran through Android Studio once the example app is opened as an Android project.

Without Android Studio, they can be ran through the terminal.

cd example
flutter build apk
cd android
./gradlew test

XCTests (iOS)

XCUnitTests are typically configured to run with cocoapods in this repo. To run all the XCUnitTests for a plugin:

cd ios
pod lib lint --allow-warnings

XCUITests aren't usually configured with cocoapods in this repo. They are configured in a xcode workspace target named RunnerUITests. To run all the XCUITests in a plugin, follow the steps in a regular iOS development workflow here

For convenience, a flutter_plugin_tools command xctest could also be used to run all the XCUITests in the repo:

pub global activate flutter_plugin_tools
cd <path_to_plugins>/packages
pub global run flutter_plugin_tools xctest --target RunnerUITests --skip <plugins_to_skip>

Contributing code

We gladly accept contributions via GitHub pull requests.

Please peruse our style guide before working on anything non-trivial. These guidelines are intended to keep the code consistent and avoid common pitfalls.

To start working on a patch:

  • git fetch upstream
  • git checkout upstream/master -b <name_of_your_branch>
  • Hack away.
  • Verify changes with flutter_plugin_tools
pub global activate flutter_plugin_tools
pub global run flutter_plugin_tools format --plugins plugin_name
pub global run flutter_plugin_tools analyze --plugins plugin_name
pub global run flutter_plugin_tools test --plugins plugin_name
  • git commit -a -m "<your informative commit message>"
  • git push origin <name_of_your_branch>

To send us a pull request:

  • git pull-request (if you are using Hub) or go to https://github.com/flutter/plugins and click the “Compare & pull request” button

Please make sure all your checkins have detailed commit messages explaining the patch.

Plugins tests are run automatically on contributions using Cirrus CI. However, due to cost constraints, pull requests from non-committers may not run all the tests automatically.

Once you've gotten an LGTM from a project maintainer and once your PR has received the green light from all our automated testing, wait for one the package maintainers to merge the pull request and pub submit any affected packages.

You must complete the Contributor License Agreement. You can do this online, and it only takes a minute. If you‘ve never submitted code before, you must add your (or your organization’s) name and contact info to the AUTHORS file.

The review process

  • This is a new process we are currently experimenting with, feedback on the process is welcomed at the Gitter contributors channel. *

Reviewing PRs often requires a non trivial amount of time. We prioritize issues, not PRs, so that we use our maintainers' time in the most impactful way. Issues pertaining to this repository are managed in the flutter/flutter issue tracker and are labeled with “plugin”. Non trivial PRs should have an associated issue that will be used for prioritization. See the prioritization section in the Flutter wiki to understand how issues are prioritized.

Newly opened PRs first go through initial triage which results in one of:

  • Merging the PR - if the PR can be quickly reviewed and looks good.
  • Closing the PR - if the PR maintainer decides that the PR should not be merged.
  • Moving the PR to the backlog - if the review requires non trivial effort and the issue isn't a priority; in this case the maintainer will:
    • Make sure that the PR has an associated issue labeled with “plugin”.
    • Add the “backlog” label to the issue.
    • Leave a comment on the PR explaining that the review is not trivial and that the issue will be looked at according to priority order.
  • Starting a non trivial review - if the review requires non trivial effort and the issue is a priority; in this case the maintainer will:
    • Add the “in review” label to the issue.
    • Self assign the PR.

The release process

We push releases manually. Generally every merged PR upgrades at least one plugin‘s pubspec.yaml, so also needs to be published as a package release. The Flutter team member most involved with the PR should be the person responsible for publishing the package release. In cases where the PR is authored by a Flutter maintainer, the publisher should probably be the author. In other cases where the PR is from a contributor, it’s up to the reviewing Flutter team member to publish the release instead.

Some things to keep in mind before publishing the release:

  • Has CI ran on the master commit and gone green? Even if CI shows as green on the PR it‘s still possible for it to fail on merge, for multiple reasons. There may have been some bug in the merge that introduced new failures. CI runs on PRs as it’s configured on their branch state, and not on tip of tree. CI on PRs also only runs tests for packages that it detects have been directly changed, vs running on every single package on master.
  • Publishing is forever. Hopefully any bugs or breaking in changes in this PR have already been caught in PR review, but now's a second chance to revert before anything goes live.
  • “Don't deploy on a Friday.” Consider carefully whether or not it‘s worth immediately publishing an update before a stretch of time where you’re going to be unavailable. There may be bugs with the release or questions about it from people that immediately adopt it, and uncovering and resolving those support issues will take more time if you're unavailable.

Releasing a package is a two-step process.

  1. Push the package update to pub.dev using pub publish.
  2. Tag the commit with git in the format of <package_name>-v<package_version>, and then push the tag to the flutter/plugins master branch. This can be done manually with git tag $tagname && git push upstream $tagname while checked out on the commit that updated version in pubspec.yaml.

We've recently updated flutter_plugin_tools to wrap both of those steps into one command to make it a little easier. This new tool is experimental. Feel free to fall back on manually running pub publish and creating and pushing the tag in git if there are issues with it.

Install the tool by running:

$ pub global activate flutter_plugin_tools

Then, from the root of your local flutter/plugins repo, use the tool to publish a release.

$ pub global run flutter_plugin_tools publish-plugin --package $package

By default the tool tries to push tags to the upstream remote, but that and some additional settings can be configured. Run pub global activate flutter_plugin_tools --help for more usage information.

The tool wraps pub publish for pushing the package to pub, and then will automatically use git to try and create and push tags. It has some additional safety checking around pub publish too. By default pub publish publishes everything, including untracked or uncommitted files in version control. flutter_plugin_tools publish-plugin will first check the status of the local directory and refuse to publish if there are any mismatched files with version control present.

There is a lot about this process that is still to be desired. Some top level items are being tracked in flutter/flutter#27258.