Validate scopes in OpenApiDocumentProvider tests and fix scope

[captainsafia]

This PR resolves an issue where an IOptionsSnapshot<> instance was incorrectly resolved from the root provider. It also updates the tests for OpenApiDocumentProvider to validate scopes so we can catch this issue in tests.

[halter73]

Was this customer reported?

[eerhardt]

Was this customer reported?

Do I count as a customer? 😆

I was getting an exception in dotnet/eshop that I showed @captainsafia and she knew what the problem was.

[captainsafia]

/backport to release/9.0

[github-actions]

Started backporting to release/9.0: https://github.com/dotnet/aspnetcore/actions/runs/11258408430

[epsitec]

I am experiencing crashes when using OpenApi. The code responsible for the crash is in OpenApiDocumentProvider, when it calls GetRequiredService<IOptionsSnapshot<OpenApiOptions>>(). Apparently, this has been fixed:

aspnetcore/src/OpenApi/src/Services/OpenApiDocumentProvider.cs

Line 28 in 81a2bab

var options = serviceProvider.GetRequiredService<IOptionsMonitor<OpenApiOptions>>();

and should have been backported to 9.0 if I interpret this pull request correctly.

However, in the NuGet package version 9.0.0 available online, the fix is missing!?
Any chance you, @captainsafia could have a look at this?

Here is a screenshot of what I am seeing:

[martincostello]

Based on #58320 (comment), the fix wasn't actually backported as it was thought to be practically impossible.

If you're seeing it in .NET 9.0.0, then maybe not.

[epsitec]

So I will review my code and try to understand what I am doing, which triggers this impossible situation.