We’ve recently adopted the PSR-2 coding standard on our application. We’ve always followed an informal coding standard but we decided it made sense to bite the bullet and fully adhere to PSR-2. If PSR-2 is new to you, it’s a coding style guide that was developed by the PHP Framework Interopability Group Group (aka PHP-FIG) to aid the sharing of code by enforcing a common standard:
PSR-2’s purpose is to have a single style guide for PHP code that results in uniformly formatted shared code.
Agreeing to adopt a coding standard is one thing, but enforcing it is another. With developers across different environments, using their own choice of editor, enforcing a set of rules can be difficult. Personally, I use PhpStorm, but occasionally i’ll do something in Atom, or Vim.
We were keen to make sure that adoption of PSR-2 would be friction-free, but consistently adopted. In this regard it made sense that it could be added to our workflow in a way that was mandatory. Encouraging devs to add rules to their editor would be a pain to maintain, and easy to override. You just know that some dev’s are really going to struggle giving up their tabs!
The popular PHP_CodeSniffer (phpcs) tool allows checking against various coding standards, and automatic fixing via PHP Code Beautifier and Fixer (phpcbf). It made sense to make use of these external tools, enforcing their versions via Composer and hooking into that workflow.
Git is central to our development workflow. No code can be merged into our codebase without first being peer reviewed via a pull-request, and then merged by another team member. It made sense then that the phpcs checks we required were enforced by Git, and in this case a Git pre-commit hook. There’s a few tricks in how we set this up (further blog post coming soon!).
First thing was to get phpcs itself installed with the required coding standard. This was done by installing the following packages into the dev section of our
Once installed it was just a case of creating the hook itself in
.git/hooks/PRE-COMMIT. Much of this code was taken from a gist i’ve seen in many places. I would happily credit the original author but I have no idea who it was.
The original code for the hook file runs the supplied changes through phpcs and checks them against the PSR2 standard. However, I added a few additional things that were useful to us. First of all I added a dependency on an environment variable we would force all our developers to add. This variable would set your default preference for whether the check runs. As much as we wanted the check to always run, we decided on reflection there may be times where we want to disable it. This would now be possible via temporary overriding of the variable by running
APPLY_CODE_STYLE=false git commit. The other enhancement I added was an interactive question for whether the user would like
phpcbf to automagically fix all errors it was able to.
With this workflow in place, it became the standard that any new commit would highlight where code was not following psr2 and attempt to fix it for you. However, at this stage we still hadn’t enforced the very presence of the hook we wanted to be reliant on. I will cover that in a new blog post shortly.