Optionally skip creating adding at_exit hook

[ileitch]

Hey,

I'm working on a gem to use Coverage in production environments. I noticed that SimpleCov always creates and at_exit hook. In my gem coverage will be handled on a per-request basis. For Rails coverage will be started & stopped in an around_filter.

What do you think would be a nice API for using SimpleCov without the at_exit behavior?

One possibility is a file simplecov/no_defaults.rb or similar that simply does not require defaults.rb

[colszowka]

Yes, I saw you mentioning this on twitter. Great! I was thinking about such a thing for a while, but never quite got to something working.

I think what you would need would be more programmatic access to the result formatting API. Basically, you can already use the result formatting by hand using the formatting code in the existing default exit hook. The problem with this whole thing might be the global scope of the SimpleCov configs. For capturing (and storing the reports of) individual requests, you probably will want per-request configuration instances (i.e. to set the output path to something that includes controller#action) as the current approach is likely to fail in threaded environments. But then again, the behaviour of the Coverage STDLIB is global in nature as well, so even if SimpleCov provided more fine-grained control by allowing users to create separate instances, the Coverage report would still apply to all code that has run in that Coverage run, so it would probably be of no use.

Also just added a comment to your corresponding PR :)