[wasm][testing] hosting webSocket echo server in xharness process

[pavelsavara]

In case that we are running unit tests in xharness, we would like to be able to host webserver in the xharness process rather than to call external servers in azure.

That would allow us to move some unit tests from outer loop to inner loop. See dotnet/runtime#52923

Part of overall epic dotnet/runtime#42852

    <WasmXHarnessArgs>$(WasmXHarnessArgs) --set-web-server-http-env=DOTNET_TEST_WEBSOCKETHOST,DOTNET_TEST_HTTPHOST</WasmXHarnessArgs>
    <WasmXHarnessArgs>$(WasmXHarnessArgs) --set-web-server-https-env=DOTNET_TEST_SECUREWEBSOCKETHOST,DOTNET_TEST_SECUREHTTPHOST</WasmXHarnessArgs>
    <WasmXHarnessArgs>$(WasmXHarnessArgs) --web-server-middleware=$(ArtifactsDir)bin/MonoNetTestServer/$(NetCoreAppCurrent)-$(Configuration)/MonoNetTestServer.dll,GenericHandler</WasmXHarnessArgs>
    <WasmXHarnessArgs>$(WasmXHarnessArgs) --web-server-middleware=$(ArtifactsDir)bin/NetCoreServer/$(NetCoreAppCurrent)-$(Configuration)/NetCoreServer.dll,GenericHandler</WasmXHarnessArgs>


set XHARNESS_CLI_PATH=c:\Dev\xharness\artifacts\bin\Microsoft.DotNet.XHarness.CLI\Debug\net6.0\Microsoft.DotNet.XHarness.CLI.dll
set XHARNESS_COMMAND=test-browser
./dotnet build /t:Test src/libraries/System.Net.WebSockets.Client/tests /p:TargetOS=Browser /p:TargetArchitecture=wasm /p:Configuration=Release

[pavelsavara]

@lewing

[pavelsavara]

@akoeplinger could you please comment on topics in the description ? Thank you.

[pavelsavara]

Right now, I'm thinking that the new echo endpoints should stay in runtime repository in form of assembly, which could be offered to xharness as a binary plugin.
That would be better than current PR state, because the test would be in same repo as tested code.
For example I would like to create unit test for dotnet/runtime#51041, which will need server side. Ideally on single PR.

It would still leave us with .NET 4.7 version of the CoreFxNetCloudService and another .net core version for xharness. Unless we convert whole CoreFxNetCloudService to .net core.

@lewing your thoughts ?

[radical]

Could you please explain what this is doing, and why, in the PR description?

[pavelsavara]

great feedback @radical, thanks!

[radical]

The environment var expansion stuff could maybe be done outside the wasm commands, but that can be done later when we can see how they get used for non-wasm cases.

LGTM! Thank you for the PR, and patience with the feedback 👍

[akoeplinger]

Missed the ping on this one, looks good to me thank you!