Request for Feedback: Getting SimpleCov to work with Spring

[ndbroadbent]

Hello!

I think I've figured out a good way to get SimpleCov working with Spring. For my Rails application, preloading the app would require some classes in my ./app directory, and this would cause some inaccurate coverage to be reported (any lines that were required during preloading were missing in the coverage.) I figured out how to fix this issue by starting SimpleCov in config/spring.rb, storing the preloaded coverage before forking the process, and then merging the coverage together in SimpleCov.result. Here's the code I'm using. (And here's a longer write-up about how I investigated this issue.)

I was wondering what you think about these changes, and if it might be possible to add some of these changes to SimpleCov?

I'm also not sure if this is just a bug in the Coverage library for my version of Ruby (2.5.5), where the coverage is being reset after the Ruby process is forked.

Thanks for your time!

[PragTob]

@ndbroadbent sorry for the long silence - it's not always easy to make time for OSS :)

Thanks for your time investigating this and working on this! 💚

I believe the behaviour when forking is inherently tied to how the coverage library works but not certain.

I'm not sure I 100% understand your approach but basically you carry coverage over. Wouldn't that mean if I ran rspec spec/models and then rspec spec/controllers later the coverage result would include both although I just ran one of them?

(not super familiar with when Spring forks, it has caused me enough pain over time that I usually disable it)