Show Razor build errors in non build server scenarios (#2737)

Author: ajaybhargavb

src/Microsoft.AspNetCore.Razor.Tools/Program.cs

@@ -40,6 +40,9 @@ public static int Main(string[] args)
             outputWriter.Dispose();
             errorWriter.Dispose();
 
+            Console.Write(output);
+            Console.Error.Write(error);
+
             // This will no-op if server logging is not enabled.
             ServerLogger.Log(output);
             ServerLogger.Log(error);

test/Microsoft.NET.Sdk.Razor.Test/IntegrationTests/BuildIntegrationTest.cs

@@ -6,6 +6,7 @@
 using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Testing.xunit;
 using Microsoft.Extensions.DependencyModel;
 using Xunit;
@@ -652,6 +653,25 @@ public async Task Building_WorksWhenMultipleRazorConfigurationsArePresent()
             Assert.FileExists(result, OutputPath, "SimpleMvc21.Views.pdb");
         }
 
+        [Fact]
+        [InitializeTestProject("SimpleMvc")]
+        public async Task Build_WithoutServer_ErrorDuringBuild_DisplaysErrorInMsBuildOutput()
+        {
+            var result = await DotnetMSBuild(
+                "Build",
+                "/p:UseRazorBuildServer=false /p:RazorLangVersion=5.0",
+                suppressBuildServer: true);
+
+            Assert.BuildFailed(result);
+            Assert.BuildOutputContainsLine(
+                result,
+                $"Invalid option 5.0 for Razor language version --version; must be Latest or a valid version in range {RazorLanguageVersion.Version_1_0} to {RazorLanguageVersion.Latest}.");
+
+            // Compilation failed without creating the views assembly
+            Assert.FileExists(result, IntermediateOutputPath, "SimpleMvc.dll");
+            Assert.FileDoesNotExist(result, IntermediateOutputPath, "SimpleMvc.Views.dll");
+        }
+
         private static DependencyContext ReadDependencyContext(string depsFilePath)
         {
             var reader = new DependencyContextJsonReader();