From c2932674216e0dd72b60991fa303fbfd8867d3b1 Mon Sep 17 00:00:00 2001
From: Ajay Bhargav Baaskaran <ajbaaska@microsoft.com>
Date: Wed, 14 Feb 2018 18:52:41 -0800
Subject: [PATCH] Fixed unnecessary invocation of TagHelper target

---
 ...etCore.Razor.Design.CodeGeneration.targets | 10 ++--
 .../BuildIncrementalismTest.cs                | 60 +++++++++++++++++++
 2 files changed, 65 insertions(+), 5 deletions(-)
 create mode 100644 test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/BuildIncrementalismTest.cs

diff --git a/src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.CodeGeneration.targets b/src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.CodeGeneration.targets
index 8215f37eaf..1eb7d2baad 100644
--- a/src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.CodeGeneration.targets
+++ b/src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.CodeGeneration.targets
@@ -60,11 +60,11 @@
       -->
     <Touch
       Files="$(_RazorTagHelperInputCache)"
-      AlwaysCreate="true">
-      <Output
-        TaskParameter="TouchedFiles"
-        ItemName="FileWrites" />
-    </Touch>
+      AlwaysCreate="true" />
+
+    <ItemGroup>
+      <FileWrites Include="$(_RazorTagHelperInputCache)" />
+    </ItemGroup>
 
     <RazorTagHelper
       Debug="$(_RazorDebugTagHelperTask)"
diff --git a/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/BuildIncrementalismTest.cs b/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/BuildIncrementalismTest.cs
new file mode 100644
index 0000000000..6e2a123cdb
--- /dev/null
+++ b/test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/BuildIncrementalismTest.cs
@@ -0,0 +1,60 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
+{
+    public class BuildIncrementalismTest : MSBuildIntegrationTestBase
+    {
+        [Fact]
+        [InitializeTestProject("SimpleMvc")]
+        public async Task BuildIncremental_SimpleMvc_PersistsTargetInputFile()
+        {
+            // Arrange
+            var thumbprintLookup = new Dictionary<string, FileThumbPrint>();
+
+            // Act 1
+            var result = await DotnetMSBuild("Build", $"/p:RazorCompileOnBuild=true");
+
+            var directoryPath = Path.Combine(result.Project.DirectoryPath, IntermediateOutputPath);
+            var filesToIgnore = new[]
+            {
+                // These files are generated on every build.
+                Path.Combine(directoryPath, "SimpleMvc.csproj.CopyComplete"),
+                Path.Combine(directoryPath, "SimpleMvc.csproj.FileListAbsolute.txt"),
+            };
+            var files = Directory.GetFiles(directoryPath).Where(p => !filesToIgnore.Contains(p));
+            foreach (var file in files)
+            {
+                var thumbprint = GetThumbPrint(file);
+                thumbprintLookup[file] = thumbprint;
+            }
+
+            // Assert 1
+            Assert.BuildPassed(result);
+
+            // Act & Assert 2
+            for (var i = 0; i < 2; i++)
+            {
+                // We want to make sure nothing changed between multiple incremental builds.
+                using (var razorGenDirectoryLock = LockDirectory(RazorIntermediateOutputPath))
+                {
+                    result = await DotnetMSBuild("Build", $"/p:RazorCompileOnBuild=true");
+                }
+
+                Assert.BuildPassed(result);
+                foreach (var file in files)
+                {
+                    var thumbprint = GetThumbPrint(file);
+                    Assert.Equal(thumbprintLookup[file], thumbprint);
+                }
+            }
+        }
+    }
+}