Run tests under NetCore

[alex-bogomaz]

Summary:

• upgraded all *.netcore.fsproj to 2.0 SDK
• ported Suave.LibUv to netstandard 2.0, becase some APIs are missing in netstandard 1.6 (like BeginThreadAffinity and others)
• run Suave tests under netcoreapp 2.0 (no WebSocketSharp and Suave.LibUv for netstandard 1.6)
• include NetCore tests to CI pipeline
• remove dependency on specific version of Suave for other NetCore NuGet packages

Notes:

• Http.fs - need to wait for NetCore release. Now using full-framework package. //cc @seanamos and @ivpadim
• Linux tests are running only with "LibUv TCP engine".
  Reason: some tests (which start and stop server) are failing with "Default TCP engine" - it is not possible on Linux to dispose socket and re-bind - https://github.com/dotnet/corefx/issues/24562.

We can do something similar as for Kestrel: aspnet/KestrelHttpServer#2111, but this requires building Suave for netstandard 2.0, since there are no Handle property for Socket under 1.6.

• Three Auth.fs tests are excluded because Suave cookie serialization code fails to serialize FSharpMap. Probably that code should not use DataContractJsonSerializer and use Newtonsoft instead?

• After converting to 2.0 SDK - there are a lot of build warnings like

Encountered conflict between 'Runtime:..\.nuget\packages\microsoft.win32.registry\4.0.0\runtimes\unix\lib\netstan
dard1.3\Microsoft.Win32.Registry.dll' and 'Runtime:..\olbog\.nuget\packages\microsoft.win32.registry\4.0.0\runtimes\win\lib\nets
tandard1.3\Microsoft.Win32.Registry.dll'.  Could not determine winner due to equal file and assembly versions.

but according to this dotnet/standard#505 we may skip those warnings

[ademar]

This is very very cool, thank you very much :)

[ademar]

@alex-bogomaz can we merge this one ?

[alex-bogomaz]

Yes - we can merge.

Netcore tests still depend on net46 "HTTP.fs", but it is OK, since netcore supports referencing full-framework libraries (as long as they work).
We may not wait for netcore release of "HTTP.fs", but rather reference it when it will will be ready.

[ademar]

Thanks!