Skip to content

How to contribute

First of all, thanks for contributing!

This document provides some basic guidelines for contributing to this repository. To propose improvements or fix a bug, feel free to submit a PR.

Before we can accept your contributions you have to sign the Contributor License Agreement


To build the Arduino CLI from sources you need the following tools to be available in your local environment:

  • Go version 1.12 or later
  • Taskfile to help you run the most common tasks from the command line

If you want to run integration tests you will also need:

  • A serial port with an Arduino device attached
  • A working Python environment, version 3.5 or later

If you're working on the gRPC interface you will also have to:

  • download the protoc compiler
  • run go get -u

Building the source code

From the project folder root, just run:

task build

The project uses Go modules so dependencies will be downloaded automatically; at the end of the build, you should find an arduino-cli executable in the same folder.

Running the tests

There are several checks and test suites in place to ensure the code works as expected and is written in a way that's consistent across the whole codebase. To avoid pushing changes that will cause the CI system to fail, you can run most of the tests locally.

To ensure code style is consistent, run:

task check

To run unit tests:

task test-unit

To run integration tests (these will take some time and require special setup, see following paragraph):

task test-integration

Running only some tests

By default, all tests from all go packages are run. To run only unit tests from one or more specific packages, you can set the TARGETS environment variable, e.g.:

TARGETS=./arduino/cores/packagemanager task test-unit

Alternatively, to run only some specific test(s), you can specify a regex to match against the test function name:

TEST_REGEX='^TestTryBuild.*' task test-unit

Both can be combined as well, typically to run only a specific test:

TEST_REGEX='^TestFindBoardWithFQBN$' TARGETS=./arduino/cores/packagemanager task test-unit

Integration tests

Being a command line interface, Arduino CLI is heavily interactive and it has to stay consistent in accepting the user input and providing the expected output and proper exit codes. On top of this, many Arduino CLI features involve communicating with external devices, most likely through a serial port, so unit tests can only go so far in giving us confidence that the code is working.

For these reasons, in addition to regular unit tests the project has a suite of integration tests that actually run Arduino CLI in a different process and assess the options are correctly understood and the output is what we expect.

To run the full suite of integration tests you need an Arduino device attached to a serial port and a working Python environment. Chances are that you already have Python installed in your system, if this is not the case you can download the official distribution or use the package manager provided by your Operating System.

Some dependencies need to be installed before running the tests and to avoid polluting your global Python environment with dependencies that might be only used by the Arduino CLI, you can use a virtual environment. There are many ways to manage virtual environments, for example you can use a productivity tool called hatch. First you need to install it (you might need to sudo the following command):

pip3 install --user hatch

Then you can create a virtual environment to be used while working on Arduino CLI:

hatch env arduino-cli

At this point the virtual environment was created and you need to make it active every time you open a new terminal session with the following command:

hatch shell arduino-cli

From now on, every package installed by Python will be confined to the arduino-cli virtual environment, so you can proceed installing the dependencies required with:

pip install -r test/requirements.txt

If the last step was successful, you should be able to run the tests with:

task test-integration

Working on docs

Documentation consists of several Markdown files stored under the docs folder at the root of the repo. Some of those files are automatically generated in the CI pipeline that builds the documentation website so you won't find them in the git repository and you need to generate them locally.

If you're working on docs and your changes are not trivial, you might want to preview the documentation website locally, before opening a Pull Request. To run the docs toolchain locally you need to have:

  • Go version 1.12 or later
  • Taskfile to help you run the most common tasks from the command line
  • A working Python environment, version 3.5 or later

Before running the toolchain, perform the following operations:

  • go get -u

When working on docs, you can launch a command that will take care of generating the docs, build the static website and start a local server you can access with your browser to see a preview of your changes - to launch this command do:

task docs:serve

If you don't see any error, hit with your browser.

Pull Requests

In order to ease code reviews and have your contributions merged faster, here is a list of items you can check before submitting a PR:

  • Create small PRs that are narrowly focused on addressing a single concern.
  • PR titles indirectly become part of the CHANGELOG so it's crucial to provide a good record of what change is being made in the title; why it was made will go in the PR description, along with a link to a GitHub issue if it exists.
  • Write tests for the code you wrote.
  • Open your PR against the master branch.
  • Maintain clean commit history and use meaningful commit messages. PRs with messy commit history are difficult to review and require a lot of work to be merged.
  • Your PR must pass all CI tests before we will merge it. If you're seeing an error and don't think it's your fault, it may not be! The reviewer will help you if there are test failures that seem not related to the change you are making.

Additional settings

If you need to push a commit that's only shipping documentation changes or example files, thus a complete no-op for the test suite, please start the commit message with the string [skip ci] to skip the build and give that slot to someone else who does need it.

If your PR doesn't need to be included in the changelog, please start the PR title with the string [skip changelog]