thoughtbot--shoulda-matchers/CONTRIBUTING.md

Contributing to Shoulda Matchers

We've put a lot of work into making improvements to Shoulda Matchers, but we always welcome changes and improvements from the community!

If you'd like to propose a change to the gem, whether it's a fix for a problem you've been running into or an idea for a new feature you think would be useful, here's how the process works:

1. Read and understand the Code of Conduct.
2. Fork this repo and clone your fork to somewhere on your machine.
3. Ensure that you have a working environment.
4. Read up on the architecture of the gem, how to run tests, and the code style we use in this project.
5. Cut a new branch and write a failing test for the feature or bugfix you plan on implementing.
6. Make sure your branch is well managed as you go along.
7. Update the inline documentation if you're making a change to the API.
8. Refrain from updating the changelog.
9. Finally, push to your fork and submit a pull request.

Although we maintain the gem in our free time, we try to respond within a day or so. After submitting your PR, we may give you feedback. For instance, we may suggest some changes to make to your code to fit within the project style or discuss alternate ways of addressing the issue in question. Assuming we're happy with everything, we'll bring your changes into master!

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Code of Conduct

If this is your first time contributing, please read the Code of Conduct. We want to create a space in which everyone is allowed to contribute, and we enforce the policies outline in this document.

Setting up your environment

The setup script will install all dependencies necessary for working on the project:

bin/setup

Architecture

This project follows the typical structure for a gem: code is located in lib and tests are in spec.

All of the matchers are broken up by the type of example group they apply to:

• {lib,spec/unit}/shoulda/matchers/action_controller* for ActionController matchers
• {lib,spec/unit}/shoulda/matchers/active_model* for ActiveModel matchers
• {lib,spec/unit}/shoulda/matchers/active_record* for ActiveRecord matchers
• {lib,spec/unit}/shoulda/matchers/independent* for matchers that can be used in any example group

There are other files in the project, of course, but there are likely the ones that you'll be interested in.

In addition, tests are broken up into two categories:

• spec/unit
• spec/acceptance

A word about the tests, by the way: they're admittedly the most complicated part of this gem, and there are a few different strategies that we've introduced at various points in time to set up objects for tests across all specs, some of which are old and some of which are new. The best approach for writing tests is probably to copy an existing test in the same file as where you want to add a new test.

Code style

We follow a derivative of the unofficial Ruby style guide created by the Rubocop developers. You can view our Rubocop configuration here, but here are some key differences:

• Use single quotes for strings.
• When breaking up methods across multiple lines, place the . at the end of the line instead of the beginning.
• Don't use conditional modifiers (i.e. x if y); place the beginning and ending of conditionals on their own lines.
• Use an 80-character line-length except for describe, context, it, and specify lines in tests.
• For arrays, hashes, and method arguments that span multiple lines, place a trailing comma at the end of the last item.
• Collection methods are spelled detect, inject, map, and select.

Running tests

Unit tests

Unit tests are the most common kind of tests in the gem. They exercise matcher code file by file in the context of a real Rails application. This application is created and loaded every time you run rspec. Because of this, it can be expensive to run individual tests. To save time, the best way to run unit tests is by using Zeus.

You'll want to start by running zeus start in one shell. Then in another shell, instead of using bundle exec rspec to run tests, you'll use bundle exec zeus rspec. So for instance, you might say:

bundle exec zeus rspec spec/unit/shoulda/matchers/active_model/validate_inclusion_of_matcher_spec.rb

Acceptance tests

The acceptance tests exercise matchers in the context of a real Ruby or Rails application. Unlike unit tests, this application is set up and torn down for each test.

Whereas you make use of Zeus to run unit tests, you make use of Appraisal for acceptance tests. Appraisal lets you run tests against multiple versions of Rails and Ruby, and in fact, this is baked into the test suite. This means that if you're trying to run a single test file, you'll need to specify which appraisal to use. For instance, you can't simply say:

bundle exec rspec spec/acceptance/active_model_integration_spec.rb

Instead, you need to say

bundle exec appraisal 5.1 rspec spec/acceptance/active_model_integration_spec.rb

Managing your branch

• Use well-crafted commit messages, providing context if possible. tpope's guide was a wonderful piece on this topic when it came out and we still find it to be helpful even today.
• Squash "WIP" commits and remove merge commits by rebasing. We try to keep our commit history as clean as possible.

Documentation

As you navigate the codebase, you may notice that each class and method in the public API is prefaced with inline documentation, which can be viewed online. This documentation is written and generated using YARD.

We ensure that the documentation is up to date before we issue a release, but sometimes we don't catch everything. So if your changes end up extending or updating the API, it's a big help if you can update the documentation to match and submit those changes in your PR.

A word on the changelog

You may also notice that we have a changelog in the form of NEWS.md. You may be tempted to include changes to this in your branch, but don't worry about this -- we'll take care of it!