Tests: Switch to PHPUnit

[drupol]

This PR:

• Switch to PHPUnit framework and get rid of PHPSpec.
• Use a contrib plugin for PHPUnit to compare iterables: https://github.com/loophp/phpunit-iterable-assertions
• Depends on Use loophp/iterators #228 because the PHPUnit plugin needs a ClosureIterator so I created loophp/iterators to use it in loophp/collection and loophp/phpunit-iterable-assertions.
• Add a phpunit.xml configuration file
• Use PHP 7.4 and 8.1 on continuous integration
• Fix issue with infection, see [Support request] Infection tests are either uncovered or skipped. infection/infection#1615
• Investigate why Infection score is different on PHP 7.4 and 8.1.

This is a huge work - I'm testing the best way to implement tests. So far I tested:

• One file per test - One dataprovider per file
• One big file containing all the dataproviders and one single test

I really like having one single basic tests and multiple dataproviders... if you have a better idea, let me know.

Follows #173

[sanmai]

THB I don't understand what's going on here. That GrumPHP thing might be at fault. If I run Infection like so:

vendor/bin/infection -j4

I have no issues whatsoever. I get:

879 mutations were generated:
     534 mutants were killed
     268 mutants were not covered by tests
      70 covered mutants were not detected
       6 errors were encountered
       0 syntax errors were encountered
       1 time outs were encountered
       0 mutants required more time than configured

Metrics:
         Mutation Score Indicator (MSI): 61%
         Mutation Code Coverage: 69%
         Covered Code MSI: 88%

[drupol]

THB I don't understand what's going on here. That GrumPHP thing might be at fault. If I run Infection like so:

Try: ./vendor/bin/grumphp --tasks=infection -vvv to get the command it runs:

Command: '/home/pol/dev/git/collection/vendor/bin/infection' '--no-interaction' '--ignore-msi-with-no-mutations' '--threads=4' '--test-framework=phpunit' '--configuration=infection.json' '--min-msi=90' '--min-covered-msi=90'

[sanmai]

Ah, looks like you need to raise the timeout:

611 mutants required more time than configured

It is set to 10 seconds now. You can try bumping it to 20 or all 30 seconds.

[drupol]

Thanks for helping @sanmai ! Going to close the issue I opened with the solution.

[drupol]

Ok ! I have the confirmation of what I thought ! Thanks !!!

[drupol]

Got another feedback from @maks-rafalko on Slack

[sanmai]

I can second this. It also runs quite a bit faster on PHP 8 👍

[drupol]

Ok, this PR is done. Ready for review.

[AlexandruGG]

Great work on this @drupol! 🚀

[drupol]

Pheew ! It's done.