[wasm] First attempt at a wasm app host (#68696)

First attempt at implementing a wasm app host

Regular dotnet apps can be run with `dotnet run`. But this is not the case for
wasm apps. We use `xharness` to run the test apps that we generate for library
tests.

Templates for browser, and console wasm projects were added recently, but they
have to be run manually by either invoking a v8 script, or running a
`http-server` in the bundle directory. Though to use a debugger with this
requires starting the debug proxy separately, and connecting few bits.

# WasmAppHost

This PR adds a new `WasmAppHost`, which can be used through `dotnet run`:

- it can run "wasm app" from it's `AppBundle` directory, using various hosts
  like `v8`, `node`, or a browser. An example use:

    ```
    $ dotnet new wasmconsole
    $ dotnet run
    WasmAppHost --runtime-config /tmp/c0/bin/Debug/net7.0/browser-wasm/AppBundle//c0.runtimeconfig.json
    [02:26:40] info: host[0] Running: node main.cjs
    [02:26:40] dbug: host[0] Using working directory: /tmp/c0/bin/Debug/net7.0/browser-wasm/AppBundle
    Incoming arguments:
    Application arguments:
    Debugger.Debug: DEBUGGING ENABLED

    mono_wasm_runtime_ready fe00e07a-5519-4dfe-b35a-f867dbaf2e28
    Could not find symbols file dotnet.js.symbols. Ignoring.
    Initializing.....
    Hello, Console!
    ```

    The console template project is run with `node` by default.

- it supports a `--debug` parameter, which (for the browser case) would startup
  a webserver, and the debug proxy for Chrome, and firefox.

```
$ dotnet new wasmbrowser

$ dotnet run --debug
WasmAppHost --runtime-config /workspaces/test/br0/bin/Debug/net7.0/browser-wasm/AppBundle//br0.runtimeconfig.json --debug --forward-console
Debug proxy for chrome now listening on http://127.0.0.1:9300/. And expecting chrome at http://localhost:9222/
Hosting environment: Production
Content root path: /workspaces/test/br0/bin/Debug/net7.0/browser-wasm/AppBundle
Now listening on: http://127.0.0.1:9300
Debug proxy for firefox now listening on tcp://127.0.0.1:6300. And expecting firefox at port 6000 .

App url: http://127.0.0.1:9000/index.html
App url: https://127.0.0.1:38331/index.html
```

- This enables using `dotnet run` with wasm samples, and library tests too.

## How do I try this out?

You'll need a dotnet with the updated packs. For now, you can use:

```
$ ./dotnet.sh build -p:TargetOS=Browser -p:TargetArchitecture=wasm -p:Configuration=Release src/tests/BuildWasmApps/Wasm.Build.Tests/Wasm.Build.Tests.csproj /t:InstallWorkloadUsingArtifacts
```

.. which would install a sdk in `artifacts/bin/dotnet-workload` with all the packs installed.

- Use that dotnet to create console, or browser wasm apps from templates, for example `dotnet new wasmconsole`, or `dotnet new wasmbrowser`.

### Debugging library tests

```
runtime$ ./artifacts/bin/dotnet-workload/dotnet run -f net7.0 -r browser-wasm -c $YourRuntimeConfig --project src/libraries/System.Buffers/tests/System.Buffers.Tests.csproj -p:DebuggerSupport=true --debug --host browser
```

- If the runtime was built in `Release` config, then you need to add `-p:DebuggerSupport=true`, so the pdbs would get deployed
- And use `--debug` to start the debugger

- Opening the url will show a `Run tests` button, which you can click after connecting with the IDE, to start running the tests

## Notes, and TODO

- `WasmAppHost`, along with the debug proxy are bundled in the `WebAssembly.Sdk` pack right now.
  - This might be changed in the future to use the dotnet app host pack pattern, and with
    additional support adding in the Sdk.
  - This would also allow using `launchSettings.json`, similar to blazor

- `WasmAppHost` depends on host config in `runtimeconfig.json`, which can be
  controlled by a `runtimeconfig.template.json` in the project directory.

- Needs more tests, cleanup, `--help` for command line arguments
- `app-support.*js` in templates, and `test-main.js` need more work to share the code

Fixes https://github.com/dotnet/runtime/issues/67236

2 files changed, 18 insertions, 10 deletions

diff --git a/eng/testing/tests.wasm.targets b/eng/testing/tests.wasm.targets
index 0981950df46..f4a2c8beea2 100644
--- a/eng/testing/tests.wasm.targets
+++ b/eng/testing/tests.wasm.targets
@@ -55,15 +55,8 @@
     <SetScriptCommands Condition="'$(JSEngineArgs)' != ''" Include="set &quot;JS_ENGINE_ARGS=$(JSEngineArgs)&quot;" />
     <SetScriptCommands Condition="'$(_WasmMainJSFileName)' != ''" Include="set &quot;MAIN_JS=--js-file^=$(_WasmMainJSFileName)&quot;" />
   </ItemGroup>
-  <PropertyGroup Condition="'$(RunScriptCommand)' == ''">
-    <_XHarnessArgs Condition="'$(OS)' != 'Windows_NT'">wasm $XHARNESS_COMMAND --app=. --output-directory=$XHARNESS_OUT</_XHarnessArgs>
-    <_XHarnessArgs Condition="'$(OS)' == 'Windows_NT'">wasm %XHARNESS_COMMAND% --app=. --output-directory=%XHARNESS_OUT%</_XHarnessArgs>
-
-    <_XHarnessArgs Condition="'$(IsFunctionalTest)' == 'true'"     >$(_XHarnessArgs) --expected-exit-code=$(ExpectedExitCode)</_XHarnessArgs>
-    <_XHarnessArgs Condition="'$(WasmXHarnessArgs)' != ''"         >$(_XHarnessArgs) $(WasmXHarnessArgs)</_XHarnessArgs>
-    <_XHarnessArgs                                                 >$(_XHarnessArgs) -s dotnet.js.symbols</_XHarnessArgs>
-    <_XHarnessArgs Condition="'$(WasmXHarnessArgsCli)' != ''"      >$(_XHarnessArgs) $(WasmXHarnessArgsCli)</_XHarnessArgs>
 
+  <PropertyGroup>
     <_AppArgs Condition="'$(IsFunctionalTest)' != 'true' and '$(Scenario)' != 'BuildWasmApps' and '$(WasmMainAssemblyFileName)' == ''">--run WasmTestRunner.dll $(AssemblyName).dll</_AppArgs>
     <_AppArgs Condition="'$(IsFunctionalTest)' != 'true' and '$(WasmMainAssemblyFileName)' != ''">--run $(WasmMainAssemblyFileName)</_AppArgs>
     <_AppArgs Condition="'$(IsFunctionalTest)' == 'true'">--run $(AssemblyName).dll</_AppArgs>
@@ -71,6 +64,16 @@
     <_AppArgs Condition="'$(WasmTestAppArgs)' != ''">$(_AppArgs) $(WasmTestAppArgs)</_AppArgs>
 
     <WasmXHarnessMonoArgs Condition="'$(XunitShowProgress)' == 'true'">$(WasmXHarnessMonoArgs) --setenv=XHARNESS_LOG_TEST_START=1</WasmXHarnessMonoArgs>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(RunScriptCommand)' == ''">
+    <_XHarnessArgs Condition="'$(OS)' != 'Windows_NT'">wasm $XHARNESS_COMMAND --app=. --output-directory=$XHARNESS_OUT</_XHarnessArgs>
+    <_XHarnessArgs Condition="'$(OS)' == 'Windows_NT'">wasm %XHARNESS_COMMAND% --app=. --output-directory=%XHARNESS_OUT%</_XHarnessArgs>
+
+    <_XHarnessArgs Condition="'$(IsFunctionalTest)' == 'true'"     >$(_XHarnessArgs) --expected-exit-code=$(ExpectedExitCode)</_XHarnessArgs>
+    <_XHarnessArgs Condition="'$(WasmXHarnessArgs)' != ''"         >$(_XHarnessArgs) $(WasmXHarnessArgs)</_XHarnessArgs>
+    <_XHarnessArgs                                                 >$(_XHarnessArgs) -s dotnet.js.symbols</_XHarnessArgs>
+    <_XHarnessArgs Condition="'$(WasmXHarnessArgsCli)' != ''"      >$(_XHarnessArgs) $(WasmXHarnessArgsCli)</_XHarnessArgs>
 
     <!-- There two flavors of WasmXHarnessArgs and WasmXHarnessMonoArgs, one is MSBuild property and the other is environment variable -->
     <RunScriptCommand Condition="'$(OS)' != 'Windows_NT'">$HARNESS_RUNNER $(_XHarnessArgs) %24XHARNESS_ARGS %24WasmXHarnessArgs -- $(WasmXHarnessMonoArgs) %24WasmXHarnessMonoArgs $(_AppArgs) %24WasmTestAppArgs</RunScriptCommand>
@@ -102,6 +105,11 @@
   <PropertyGroup>
     <BundleTestWasmAppDependsOn Condition="'$(BuildAOTTestsOn)' == 'local'">WasmTriggerPublishApp</BundleTestWasmAppDependsOn>
     <BundleTestWasmAppDependsOn Condition="'$(BuildAOTTestsOnHelix)' == 'true'">$(BundleTestWasmAppDependsOn);_BundleAOTTestWasmAppForHelix</BundleTestWasmAppDependsOn>
+
+    <RunCommand>$(WasmAppHostDir)/WasmAppHost</RunCommand>
+    <!-- Use BundleDir here, since WasmAppDir is set in a target, and `dotnet run` reads
+         $(Run*) without running any targets -->
+    <RunArguments>--runtime-config $(BundleDir)/WasmTestRunner.runtimeconfig.json $(WasmHostArguments) $(StartArguments) $(WasmXHarnessMonoArgs) $(_AppArgs)</RunArguments>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(BuildAOTTestsOnHelix)' == 'true'">
diff --git a/eng/testing/xunit/xunit.targets b/eng/testing/xunit/xunit.targets
index 8a950eb58ef..6b048e6f6a9 100644
--- a/eng/testing/xunit/xunit.targets
+++ b/eng/testing/xunit/xunit.targets
@@ -8,10 +8,10 @@
 
   <!-- Run target (F5) support. -->
   <PropertyGroup>
-    <RunWorkingDirectory>$(OutDir)</RunWorkingDirectory>
+    <RunWorkingDirectory Condition="'$(RunWorkingDirectory)' == ''">$(OutDir)</RunWorkingDirectory>
   </PropertyGroup>
 
-  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">
+  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' and '$(RunCommand)' == ''">
     <RunCommand>$(DotNetTool)</RunCommand>
     <RunArguments>test $(TargetPath) --settings $(OutDir).runsettings</RunArguments>
   </PropertyGroup>