A linter is a program that analyzes source code for common errors and conformance to a coding style. When working in a team, it helps to have the repository conform to the same coding style. For example, a specific team would like to have a specific template rendering system, say erb over haml. These standards tend to make a codebase consistent and hence easier to work with. Such decisions are made on a team-by-team basis and each team may have different preferences resulting in different styles being adopted. Regardless of the final decision, teams tend to benefit overall from picking a standard or style and sticking by it.
You may have noticed that most of our HTML in app/views is rendered using HAML. Our team decided to use it as it is more cross-platform, that is, you can find HAML engines in more programming languages including Java, Javascript and PHP. This makes it easy for most developers to work with the codebase.
To enforce coding standards within this project, we have setup three different linter systems that enforce this project's formatting standards. We have included tests that will enforce the linter checks in spec/linters that are run automatically on CI.
rubocop checks your
Ruby code and relies on .rubocop.yml for configuration.
You can manually do this checks with bundle exec rubocop; add -a to autocorrect some
common errors (but as always, commit before you do so!).
haml-lint, configured by
.haml-lint.yml, works on Haml files.
bundle exec haml-lint runs it manually.
Finally,
eslint, configured by
.eslintrc.js, works on JavaScript.
yarn run lint_fix runs it manually. (You can see in
package.json that lint and lint_fix are entries
in JSON path $.scripts.lint and $.scripts.lint_fix that invoke a
vendored install of eslint.)
Tip: Guard is a tool that allows you to run file watchers that run automated tasks whenever a file or directory is modified. The Guardfile specifies file watchers and tasks to run. One option is to setup Guard to run the linters every time you modify a file. To initiate guard, run the following command in a separate terminal:
bundle exec guardNext, you should read about Credentials management, Heroku setup and CI Setup