[Validator] Use Mime component to determine mime type for file validator

[pierredup]

Q	A
Branch?	4.4
Bug fix?	yes
New feature?	no
Deprecations?	no
Tickets	N/A
License	MIT
Doc PR	N/A

When validating the mime type for a file, the Validator component relies on the Symfony\Component\HttpFoundation\File\File class, but if the HttpFoundation component is not installed, then you just get the error

PHP Fatal error:  Uncaught Error: Class 'Symfony\Component\HttpFoundation\File\File' not found

This PR uses the Mime component to get the mime type for a file and throws an exception if the Mime component is not installed.

[nicolas-grekas]

Now that the Mime component is standalone, can't we skip the dependency on HttpFoundation instead?

[pierredup]

@nicolas-grekas Done

[nicolas-grekas]

What about considering it as a bugfix?

[pierredup]

What about considering it as a bugfix?

I wasn't sure if it counted as a bugfix or new feature. When in doubt, I just consider something a new feature :)

But I'm not sure if a bugfix against 3.4 can use the Mime component, so should I create a new PR for 3.4 and have the original exception message for HttpFoundation, then just rebase and retarget 4.4 here?

[nicolas-grekas]

I would suggest targeting 4.4 and forget about 3.4.

[pierredup]

Status: Ready for review

[nicolas-grekas]

I pushed a CS change. The code looks good, but the tests need some love, see failures on appveyor when the finfo extension is not enabled.

[pierredup]

I reverted the changes to the tests to use mocks again, and just changed the ordering of the checks

[fabpot]

Thank you @pierredup.