[HttpKernel] Resolve DateTime value using the Clock

[GromNaN]

Q	A
Branch?	6.3
Bug fix?	no
New feature?	yes
Deprecations?	no
Tickets	-
License	MIT
Doc PR	TODO

In order to mock the current time in functional test cases by injecting a Symfony\Component\Clock\MockClock as clock service. This is necessary when a DateTimeInterface argument is not nullable and we expect the current date time by default.

Example when 2 routes are configured on the same controller with an optional parameter.

class TvGridController
{
    #[Route('/', name: 'prime_now')]
    #[Route('/{date}', name: 'prime_date']
    public function prime(\DateTimeInterface $date)
    {
        return new Response('Grid for date: '.$date->format('Y-m-d'));
    }
}

[carsonbot]

Hey!

Thanks for your PR. You are targeting branch "6.2" but it seems your PR description refers to branch "6.3".
Could you update the PR description or change target branch? This helps core maintainers a lot.

Cheers!

Carsonbot

[GromNaN]

From php doc:

If format does not contain the character ! then portions of the generated date/time which are not specified in format will be set to the current system time.

It looks like we cannot change the reference date when using DateTime::createFromFormat. This means we cannot use the clock when format is specified.

[GromNaN]

Rebased. Ready for a last review.

[GromNaN]

I tried to use the new ClockAwareTrait from #48362, but I think we should not have symfony/clock as a required dependency to use this class.

[nicolas-grekas]

Now that #48642 is merged, what about leveraging Clock::get()->now()?
Making clock a required dep might be legit. Because this static class is just a wrapper around PSR-20, it doesn't create any strong coupling to the clock implementations in the package so it might be fine.

[GromNaN]

Dependency injection is simpler here since this is already a service, and this is easy to test. I don't see the benefit of the global object: that adds a required dependency to symfony/clock and the tests would required a call to mockTime.

[nicolas-grekas]

LGTM thanks (small rebase needed)

[nicolas-grekas]

(tests fail)

[GromNaN]

Yes sorry, that's fixed.

[nicolas-grekas]

Thank you @GromNaN.