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

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.

Prerequisites

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 board attached
  • A working Python environment, version 3.8 or later

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

  • download the protoc compiler
  • run go get -u github.com/golang/protobuf/protoc-gen-go

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.

Hardware requirements for running the full suite of integration tests:

An Arduino board attached to a serial port. The board must:

  • Use one of the VID/PID pairs used by Arduino or their partners (as is the case with all modern official Arduino boards except the classic Nano).
  • Accept uploads using the FQBN associated with that VID/PID (which will be the case unless you have installed a custom bootloader or removed the bootloader).

Note that running the integration tests will result in a sketch being uploaded to every attached Arduino board meeting the above requirements.

Software requirements for running integration tests:

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, to do so we use Poetry. First you need to install it (you might need to sudo the following command):

pip3 install --user poetry

For more installation options read the official documentation.

After Poetry has been installed you should be able to run the tests with:

task test-integration

This will automatically install the necessary dependencies, if not already installed, and run the integration tests automatically.

When editing any Python file in the project remember to run linting checks with:

task python:check

This will run flake8 automatically and return any error in the code formatting, if not already installed it will also install integration tests dependencies.

In case of linting errors you should be able to solve most of them by automatically formatting with:

task python:format

Configuration files formatting

To keep the configurations tidy and in order we use Prettier to automatically format all YAML files in the project. Keeping and enforcing a formatting standard helps everyone make small PRs and avoids the introduction of formatting changes made by unconfigured editors.

There are several ways to run Prettier. If you're using Visual Studio Code you can easily use the prettier-vscode extension to automatically format as you write.

Otherwise you can use the following tasks. To do so you'll need to install npm if not already installed. Check the official documentation to learn how to install npm for your platform.

To check if the files are correctly formatted run:

task config:check

If the output tells you that some files are not formatted correctly run:

task config:format

When opening a new Pull Request, checks are automatically run to verify that configuration files are correctly formatted. In case of failures we might ask you to update the PR with correct formatting.

Working on docs

Documentation is provided to final users in form of static HTML content generated from a tool called MkDocs and hosted on GitHub Pages.

Local development

Most of the documentation consists of static content written over several Markdown files under the docs folder at the root of this git repository but some other content is dynamically generated from the CI pipelines - this is the case with the command line reference and the gRPC interface, for example.

If you want to check out how the documentation would look after some local changes, you might need to reproduce what happens in the CI, generating the full documentation website from your personal computer. To run the docs toolchain locally, you need to have a few dependencies and tools installed:

  • Go version 1.12 or later
  • Taskfile to help you run the most common tasks from the command line
  • A working Python environment, see this paragraph if you need to setup one

Before running the toolchain, perform the following operations from the root of the git repository (if you have a Python virtual environment, activate it before proceeding):

  • go get -u github.com/pseudomuto/protoc-gen-doc/cmd/protoc-gen-doc
  • pip install -r requirements_docs.txt

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 later access with a web browser to see a preview of your changes. From the root of the git repository run:

task docs:serve

If you don't see any error, hit http://127.0.0.1:8000 with your browser to navigate the generated docs.

Docs publishing

The present git repository has a special branch called gh-pages that contains the generated HTML code for the docs website; every time a change is pushed to this special branch, GitHub automatically triggers a deployment to pull the change and publish a new version of the website. Do not open Pull Requests to push changes to the gh-pages branch, that will be done exclusively from the CI.

Docs versioning

In order to provide support for multiple Arduino CLI releases, Documentation is versioned so that visitors can select which version of the documentation website should be displayed. Unfortunately this feature isn't provided by GitHub pages or MkDocs, so we had to implement it on top of the generation process.

Before delving into the details of the generation process, here follow some requirements that were established to provide versioned documentation:

  • A special version of the documentation called dev is provided to reflect the status of the Arduino CLI on the master branch - this includes unreleased features and bugfixes.
  • Docs are versioned after the minor version of an Arduino CLI release. For example, Arduino CLI 0.99.1 and 0.99.2 will be both covered by documentation version 0.99.
  • The landing page of the documentation website will automatically redirect visitors to the most recently released version of the Arduino CLI.

To implement the requirements above, the execution of MkDocs is wrapped using a CLI tool called Mike that does a few things for us:

  • It runs MkDocs targeting subfolders named after the Arduino CLI version, e.g. documentation for version 0.10.1 can be found under the folder 0.10.
  • It injects an HTML control into the documentation website that lets visitors choose which version of the docs to browse from a dropdown list.
  • It provides a redirect to a version we decide when visitors hit the landing page of the documentation website.
  • It pushes generated contents to the gh-pages branch.

Note: unless you're working on the generation process itself, you should never run Mike from a local environment, either directly or through the Task docs:publish. This might result in unwanted changes to the public website.

Docs formatting

To keep the documentation tidy and in order we use Prettier to automatically format all Markdown files in the project. Keeping and enforcing a formatting standard helps everyone make small PRs and avoids the introduction of formatting changes made by unconfigured editors.

There are several ways to run Prettier. If you're using Visual Studio Code you can easily use the prettier-vscode extension to automatically format as you write.

Otherwise you can use the following tasks. To do so you'll need to install npm if not already installed. Check the official documentation to learn how to install npm for your platform.

To check if the files are correctly formatted run:

task docs:check

If the output tells you that some files are not formatted correctly run:

task docs:format

When opening a new Pull Request, checks are automatically run to verify that documentation is correctly formatted. In case of failures we might ask you to update the PR with correct formatting.

Docs automation

In order to avoid unwanted changes to the public website hosting the Arduino CLI documentation, only Mike is allowed to push changes to the gh-pages branch, and this only happens from within the CI, in a workflow named publish-docs.

The CI is responsible for guessing which version of the Arduino CLI we're building docs for, so that generated content will be stored in the appropriate section of the documentation website. Because this guessing might be fairly complex, the logic is implemented in a Python script called build.py. The script will determine the version of the Arduino CLI that was modified in the current commit (either dev or an official, numbered release) and whether the redirect to the latest version that happens on the landing page should be updated or not.

Internationalization (i18n)

In order to support i18n in the CLI, any messages that are intended to be translated should be wrapped in a call to i18n.Tr. This call allows us to build a catalog of translatable strings, replacing the reference string at runtime with the localized value.

Adding or modifying these messages requires an i18n update, as this process creates the reference catalog that is shared with translators. For that reason, the task check command will fail if the catalog was not updated to sync with changes to the source code.

To update the catalog, execute the following command and commit the changes.

task i18n:update

To verify that the catalog is up-to-date, you may execute the command:

task i18n:check

Example usage:

package main

import (
  "fmt"
  "github.com/arduino/arduino-cli/i18n"
)

func main() {
  fmt.Println(i18n.Tr("Hello World!"))
}

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 commit message and PR title with the string [skip changelog]