Make Extensions.FileProviders supported in browser and only unsupport FSW usage

[jozkee]

Fixes #56178

Since PhysicalFilesWatcher can be used without a FileSystemWatcher through polling, I reduced the unsupported scenarios to only the ones that actually use FSW in browser with a couple of runtime checks.
Let me know if this is not a good idea and instead we should mark the whole type as unsupported.

[ghost]

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Issue Details

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Fixes #56178

Since PhysicalFilesWatcher can be used without a FileSystemWatcher through polling, I reduced the unsupported scenarios to only the ones that actually use FSW in browser with a couple of runtime checks.
Let me know if this is not a good idea and instead we should mark the whole type as unsupported.

Author:	Jozkee
Assignees:	-
Labels:	area-Extensions-FileSystem
Milestone:	-

[safern]

LGTM

[lewing]

This enables the code but none of the tests? Did you try running any of the tests?

[jozkee]

I ran them on Windows and Ubuntu. Do you mean enable them for browser?

[lewing]

yes I meant for browser.

[jozkee]

I did not run them for browser locally, is it too cumbersome to do?
If so, I can send a PR that removes this line in the test csproj and see what happens:

runtime/src/libraries/Microsoft.Extensions.FileProviders.Physical/tests/Microsoft.Extensions.FileProviders.Physical.Tests.csproj

Line 7 in 877af80

<IgnoreForCI Condition="'$(TargetOS)' == 'Browser'">true</IgnoreForCI>

[eerhardt]

Won't this still throw PNSE when creating a PhysicalFileProvider on browser? Shouldn't the logic be something like:

(UsePollingFileWatcher && UseActivePolling) || OperatingSystem.IsBrowser() ? null : ...

[jozkee]

Ah I see, so we should always fallback to use polling on browser. That makes sense to me.

[jozkee]

FYI: PR #56257 addresses this in 276b008.