Warning on unsupported tfms (microsoft#15072)

* Add warning when restoring old TFM

* revert

* Revert "revert"

This reverts commit 81c7638.

Author: nohwnd

eng/verify-nupkgs.ps1

@@ -18,7 +18,7 @@ function Verify-Nuget-Packages {
     Write-Host "Starting Verify-Nuget-Packages."
     $expectedNumOfFiles = @{
         "Microsoft.CodeCoverage"                      = 59;
-        "Microsoft.NET.Test.Sdk"                      = 15;
+        "Microsoft.NET.Test.Sdk"                      = 20;
         "Microsoft.TestPlatform"                      = 619;
         "Microsoft.TestPlatform.Build"                = 20;
         "Microsoft.TestPlatform.CLI"                  = 481;

src/package/Microsoft.NET.Test.Sdk/Microsoft.NET.Test.Sdk.csproj

@@ -29,6 +29,9 @@
     <None Update="Microsoft.NET.Test.Sdk.props">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
+    <None Update="Microsoft.NET.Test.Sdk.targets">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
     <None Update="netcoreapp\*">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>

src/package/Microsoft.NET.Test.Sdk/Microsoft.NET.Test.Sdk.nuspec

@@ -21,10 +21,17 @@
     <file src="netstandard2.0\netcoreapp\*" target="build\net8.0\" />
     <file src="netstandard2.0\netfx\*" target="build\net462\" />
 
-    <file src="netstandard2.0\Microsoft.NET.Test.Sdk.props" target="buildMultiTargeting\" />
+    <file src="netstandard2.0\Microsoft.NET.Test.Sdk.props" target="buildMultiTargeting\net462\" />
+    <file src="netstandard2.0\Microsoft.NET.Test.Sdk.props" target="buildMultiTargeting\net8.0\" />
     <file src="netstandard2.0\Microsoft.NET.Test.Sdk.props" target="build\net8.0\" />
     <file src="netstandard2.0\Microsoft.NET.Test.Sdk.props" target="build\net462\" />
 
+    <!-- Add incompatibility warning. -->
+    <file src="netstandard2.0\Microsoft.NET.Test.Sdk.targets" target="buildMultiTargeting\netcoreapp2.0\" />
+    <file src="netstandard2.0\Microsoft.NET.Test.Sdk.targets" target="build\netcoreapp2.0\" />
+    <file src="netstandard2.0\Microsoft.NET.Test.Sdk.targets" target="buildMultiTargeting\netstandard2.0\" />
+    <file src="netstandard2.0\Microsoft.NET.Test.Sdk.targets" target="build\netstandard2.0\" />
+
     <file src="netstandard2.0\_._" target="lib/net8.0" />
     <file src="netstandard2.0\_._" target="lib/net462" />
   </files>

src/package/Microsoft.NET.Test.Sdk/Microsoft.NET.Test.Sdk.targets

@@ -0,0 +1,6 @@
+<Project InitialTargets="NonCompatibleTargetFrameworkError_Microsoft_NET_Test_Sdk_net8_0">
+  <Target Name="NonCompatibleTargetFrameworkError_Microsoft_NET_Test_Sdk_net8_0"
+          Condition="'$(SuppressTfmSupportBuildWarnings)' == ''">
+    <Warning Text="Microsoft.NET.Test.Sdk doesn't support $(TargetFramework) and has not been tested with it. Consider upgrading your TargetFramework to net8.0 or later. You may also set &lt;SuppressTfmSupportBuildWarnings&gt;true&lt;/SuppressTfmSupportBuildWarnings&gt; in the project file to ignore this warning and attempt to run in this unsupported configuration at your own risk." />
+  </Target>
+</Project>