Is there any documentation on how paratest works? I tried to look for it but without any luck :/

[hostaway-greg]

Hi,

I have few questions on how paratest works, but I cannot find any answer :/
How does test selection work?

1. Is it scanning a directory for tests, then divides them into groups and assign a worker to a group of tests?
2. Is it scanning a directory for tests, spawning workers, and picks a test out of the discovered tests?
3. other?

Can it use result cache to order test by execution time?
If yes, then does it affect how test selection/worker assignment works from the previous question?

Does small/medium/large annotation/attribute affect test selection/assignment to a worker?

Are there any entry points to modify default behavior ?

Thank you and have a nice day

[Slamdunk]

How does test selection work?

1. ParaTest asks PHPUnit in SuiteLoader to get a list of all the PHPUnit\Framework\TestCase and PHPUnit\Runner\PhptTestCase
2. WrapperRunner gets that list
3. WrapperRunner starts n empty workes
4. As soon as a worker gets free, it receivse the next test to run, see WrapperRunner:assignAllPendingTests

Can it use result cache to order test by execution time?

Not yet because while reading the cache is easy, writing it isn't. Any PR is welcome.

Does small/medium/large annotation/attribute affect test selection/assignment to a worker?

Test selection is the same as PHPUnit's one.
Test assignement isn't affected by test selection.

Are there any entry points to modify default behavior ?

No, and that's by design: reliable parallelization is a nightmare, and I don't want issues opened for unknown/external code behaviour

[hostaway-greg]

Great :) Thanks for this information. Maybe it should be added to a README?
I will look into that cache, maybe I could help. But no promisses.

[uncaught]

I would like to know some of the flow, too. Especially those things:

• How does paratest run class level code (setUpBeforeClass/tearDownAfterClass)?
  • Do those always run for every test case individually (process isolated)
  • or just by chance depending on whether the tests were assigned to the same process
  • or are test cases in one class always executed in one process?
• How does paratest handle dependent test cases (@depends/#[Depends()])?

Thank you