[wasm][workloads] Check downlevel runtime versions

eng/testing/scenarios/BuildWasmAppsJobsList.txt

@@ -47,3 +47,4 @@ Wasm.Build.Tests.WasmTemplateTests
 Wasm.Build.Tests.WorkloadTests
 Wasm.Build.Tests.MT.Blazor.SimpleMultiThreadedTests
 Wasm.Build.Tests.TestAppScenarios.DebugLevelTests
+Wasm.Build.Tests.DownlevelCheck

src/mono/wasm/Wasm.Build.Tests/DownLevelCheck.cs

@@ -0,0 +1,74 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Wasm.Build.Tests
+{
+    public class DownlevelCheck : BuildTestBase
+    {
+        public DownlevelCheck(ITestOutputHelper output, SharedBuildPerTestClassFixture buildContext)
+            : base(new TestMainJsProjectProvider(output), output, buildContext)
+        {
+        }
+
+        private const string ProjectTemplate =
+            """
+            <Project Sdk="Microsoft.NET.Sdk">
+                <PropertyGroup>
+                    <TargetFramework>{TargetFramework}</TargetFramework>
+                    <OutputType>Exe</OutputType>
+                </PropertyGroup>
+                <Target Name="PrintResolveFrameworkReferences" AfterTargets="ResolveFrameworkReferences">
+                    <Message Text="{TestMessage}" Importance="High" />
+                </Target>
+            </Project>
+            """;
+
+        private string FormatTestMessage(string version) => $"TEST::TargetingPackVersion::{version}::TEST";
+
+        public static IEnumerable<object[]> GetData() => new[]
+        {
+            new object[] { "net6.0", DownlevelVersions.PackageVersionNet6 },
+            new object[] { "net7.0", DownlevelVersions.PackageVersionNet7 },
+            new object[] { "net8.0", DownlevelVersions.PackageVersionNet8 },
+        };
+
+        [Theory]
+        [MemberData(nameof(GetData))]
+        public void TestComputedVersions(string targetFramework, Version computedVersion)
+        {
+            string id = $"DownlevelCheck_{targetFramework}_{GetRandomId()}";
+            string projectContent = ProjectTemplate
+                .Replace("{TargetFramework}", targetFramework)
+                .Replace("{TestMessage}", FormatTestMessage("@(ResolvedFrameworkReference->'%(TargetingPackVersion)')"));
+
+            InitPaths(id);
+            InitProjectDir(_projectDir);
+            File.WriteAllText(Path.Combine(_projectDir, $"{id}.csproj"), projectContent);
+            File.WriteAllText(Path.Combine(_projectDir, $"Program.cs"), "System.Console.WriteLine(\"Hello, World!\");"); // no-op
+
+            (var result, _) = BuildProjectWithoutAssert(id, "Release", new(
+                AssertAppBundle: false,
+                CreateProject: false,
+                Publish: false,
+                TargetFramework: targetFramework
+            ));
+
+            var versionExtractor = new Regex(FormatTestMessage("([0-9]+.[0-9]+.[0-9]+)"));
+            var match = versionExtractor.Match(result.Output);
+            Assert.True(match.Success, $"Expected to find a version in the output, but got: {result.Output}");
+
+            if (!Version.TryParse(match.Groups[1].Value, out var actualVersion))
+                Assert.Fail($"Unable to parse version from regex match '{match.Groups[1].Value}'");
+
+            Assert.True(actualVersion >= computedVersion, $"Actually used version is lower then computed version in repository: (actually used version) '{actualVersion}' >= (computed version in repository) '{computedVersion}'");
+        }
+    }
+}

src/mono/wasm/Wasm.Build.Tests/DownlevelVersions.cs.in

@@ -0,0 +1,8 @@
+using System;
+
+public static class DownlevelVersions
+{
+    public static readonly Version PackageVersionNet6 = Version.Parse("${PackageVersionNet6}");
+    public static readonly Version PackageVersionNet7 = Version.Parse("${PackageVersionNet7}");
+    public static readonly Version PackageVersionNet8 = Version.Parse("${PackageVersionNet8}");
+}

src/mono/wasm/Wasm.Build.Tests/Wasm.Build.Tests.csproj

@@ -46,6 +46,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.DotNet.Build.Tasks.Templating" Version="$(MicrosoftDotNetBuildTasksTemplatingVersion)" />
     <PackageReference Include="Microsoft.Playwright" Version="1.21.0" />
     <ProjectReference Include="$(RepoRoot)src\tasks\Microsoft.NET.Sdk.WebAssembly.Pack.Tasks\Microsoft.NET.Sdk.WebAssembly.Pack.Tasks.csproj" />
     <Compile Include="$(BrowserProjectRoot)debugger\DebuggerTestSuite\BrowserLocator.cs" />
@@ -55,6 +56,24 @@
     <None Include="data\**\*" Link="data\%(RecursiveDir)%(FileName)%(Extension)" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
 
+  <Target Name="GenerateVersions" BeforeTargets="CoreCompile">
+    <PropertyGroup>
+      <_DownlevelVersionsOutputPath>$(IntermediateOutputPath)\DownlevelVersions.cs</_DownlevelVersionsOutputPath>
+    </PropertyGroup>
+    <ItemGroup>
+      <_DownlevelVersionsProperty Include="PackageVersionNet6" Value="$(PackageVersionNet6)" />
+      <_DownlevelVersionsProperty Include="PackageVersionNet7" Value="$(PackageVersionNet7)" />
+      <_DownlevelVersionsProperty Include="PackageVersionNet8" Value="$(PackageVersionNet8)" />
+    </ItemGroup>
+    <GenerateFileFromTemplate
+      TemplateFile="DownlevelVersions.cs.in"
+      Properties="@(_DownlevelVersionsProperty->'%(Identity)=%(Value)')"
+      OutputPath="$(_DownlevelVersionsOutputPath)" />
+    <ItemGroup>
+      <Compile Include="$(_DownlevelVersionsOutputPath)" />
+    </ItemGroup>
+  </Target>
+
   <Target Name="UpdateRunScriptCommands" BeforeTargets="GenerateRunScript" DependsOnTargets="_SetPackageVersionForWorkloadsTesting">
     <Error Condition="'$(TestUsingWorkloads)' == 'true' and '$(PackageVersionForWorkloadManifests)' == ''" Text="%24(PackageVersionForWorkloadManifests) is not set. PackageVersion=$(PackageVersion)." />