Use xdebug-filter to reduce the time needed to collect coverage

[maks-rafalko]

Everything is explained here https://thephp.cc/news/2019/01/faster-code-coverage

Time before: 6.04 minutes
Time after: 4.05 minutes

for the same job that runs phpunit and generates coverage.

Which is a huge win IMO

[BackEndTea]

Anything that speeds up CI is a 👍 for me

Maybe we could tell our users about this as well, in order for them to speed up infection runs.

[localheinz]

👍

[maks-rafalko]

Maybe we could tell our users about this as well, in order for them to speed up infection runs.

Well, I've added a tweet from Infection account about this feature: https://twitter.com/infection_php/status/1171519807167926272

I will also add this info to the blog post about 0.14.0 and, probably, to the documentation.

Thank you @BackEndTea & @localheinz

[sanmai]

I'm sorry that I'm late to the party, but you don't have to generate xdebug-filter.php every time. It is tied to our configuration so it can be generated once, committed to the repository, and left alone.

Though it does contain some absolute paths, there's nothing a __DIR__ couldn't help with.

[maks-rafalko]

The only one reason I didn't do it is to not forget to update it after phpunit.xml is modified. But let's see, now I think it's unlikely to happen.

Opened a PR #783