Make Razor targets noop with no razor files

src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.Compilation.targets

@@ -58,7 +58,8 @@
           Outputs="@(RazorIntermediateAssembly);
                    @(_RazorDebugSymbolsIntermediatePath);
                    $(NonExistentFile)"
-          DependsOnTargets="RazorCoreGenerate">
+          DependsOnTargets="RazorCoreGenerate"
+          Condition="'@(RazorCompile)'!=''">
     <!-- These two compiler warnings are raised when a reference is bound to a different version
              than specified in the assembly reference version number.  MSBuild raises the same warning in this case,
              so the compiler warning would be redundant. -->

src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.props

@@ -11,8 +11,8 @@
     Use these properties to attach behavior to the corresponding target.
   -->
   <PropertyGroup>
-    <RazorGenerateDependsOn>_RazorResolveTagHelpers;RazorCoreGenerate</RazorGenerateDependsOn>
-    <RazorCompileDependsOn>_RazorResolveTagHelpers;RazorCoreGenerate;RazorCoreCompile</RazorCompileDependsOn>
+    <RazorGenerateDependsOn>RazorResolveGenerateInputs;RazorCoreGenerate</RazorGenerateDependsOn>
+    <RazorCompileDependsOn>RazorGenerate;RazorCoreCompile</RazorCompileDependsOn>
   </PropertyGroup>
 
   <!--

src/Microsoft.AspNetCore.Razor.Design/build/netstandard2.0/Microsoft.AspNetCore.Razor.Design.targets

@@ -37,11 +37,52 @@
     <_RazorTagHelperToolAssembly>$(_RazorMSBuildRoot)tools\Microsoft.AspNetCore.Razor.TagHelperTool.dll</_RazorTagHelperToolAssembly>
   </PropertyGroup>
 
+  <!--
+    Gathers input source files for code generation. This is a separate target so that we can avoid
+    lots of work when there are no inputs for code generation.
+
+    Notice there are plenty of Condition="'@(RazorGenerate)'!=''" to avoid running more expensive targets.
+  -->
+  <Target Name="RazorResolveGenerateInputs">
+    <ItemGroup>
+      <RazorGenerate Include="@(Content)" Condition="'%(Content.Extension)'=='.cshtml'" />
+      <_RazorGenerateOutput Include="@(RazorGenerate->'$(RazorGenerateOutputPath)%(RelativeDir)%(Filename).cs')" />
+    </ItemGroup>
+  </Target>
+
+  <Target 
+    Name="_ResolveRazorCoreGenerateInputs" 
+    DependsOnTargets="RazorResolveGenerateInputs"
+    Condition="'@(RazorGenerate)'!=''">
+
+    <PropertyGroup>
+      <_RazorGenerateHashFile>$(IntermediateOutputPath)$(MSBuildProjectName).RazorCoreGenerate.cache</_RazorGenerateHashFile>
+    </PropertyGroup>
+
+    <Hash ItemsToHash="@(RazorGenerate)" Condition="'@(RazorGenerate)'!=''">
+      <Output TaskParameter="HashResult" PropertyName="_RazorGenerateHash" />
+    </Hash>
+
+    <MakeDir
+      Directories="$(IntermediateOutputPath)"
+      Condition="!Exists('$(IntermediateOutputPath)')" />
+
+    <WriteLinesToFile
+      Lines="$(_RazorGenerateHash)"
+      File="$(_RazorGenerateHashFile)"
+      Overwrite="True"
+      WriteOnlyWhenDifferent="True" />
+
+    <ItemGroup>
+      <FileWrites Include="$(_RazorGenerateHashFile)" />
+    </ItemGroup>
+  </Target>
+
   <!-- 
     Gathers input assemblies for Tag Helper discovery and compilation. Add items to @(ReferencePath)
   -->
   <Target
-    Name="RazorResolveAssemblyReferences"
+    Name="_RazorResolveReferences"
     DependsOnTargets="ResolveReferences">
     <ItemGroup>
       <RazorReferencePath Include="@(ReferencePath)"/>
@@ -51,9 +92,10 @@
 
   <Target
     Name="_RazorResolveTagHelpers"
-    DependsOnTargets="Compile;RazorResolveAssemblyReferences"
+    DependsOnTargets="Compile;_RazorResolveReferences"
     Inputs="$(MSBuildAllProjects);@(RazorReferencePath)"
-    Outputs="$(_RazorTagHelperInputCache)">
+    Outputs="$(_RazorTagHelperInputCache)"
+    Condition="'@(RazorGenerate)'!=''">
 
     <!-- 
       We're manipulating our output directly here because we want to separate the actual up-to-date check
@@ -81,41 +123,12 @@
 
   </Target>
 
-  <Target Name="_ResolveRazorCoreGenerateInputs">
-
-    <ItemGroup>
-      <RazorGenerate Include="@(Content)" Condition="'%(Content.Extension)'=='.cshtml'" />
-      <_RazorGenerateOutput Include="@(RazorGenerate->'$(RazorGenerateOutputPath)%(RelativeDir)%(Filename).cs')" />
-    </ItemGroup>
-
-    <PropertyGroup>
-      <_RazorGenerateHashFile>$(IntermediateOutputPath)$(MSBuildProjectName).RazorCoreGenerate.cache</_RazorGenerateHashFile>
-    </PropertyGroup>
-
-    <Hash ItemsToHash="@(RazorGenerate)">
-      <Output TaskParameter="HashResult" PropertyName="_RazorGenerateHash" />
-    </Hash>
-
-    <MakeDir
-      Directories="$(IntermediateOutputPath)"
-      Condition="!Exists('$(IntermediateOutputPath)')" />
-
-    <WriteLinesToFile
-      Lines="$(_RazorGenerateHash)"
-      File="$(_RazorGenerateHashFile)"
-      Overwrite="True"
-      WriteOnlyWhenDifferent="True" />
-
-    <ItemGroup>
-      <FileWrites Include="$(_RazorGenerateHashFile)" />
-    </ItemGroup>
-  </Target>
-
   <Target
     Name="RazorCoreGenerate"
     DependsOnTargets="_ResolveRazorCoreGenerateInputs;_RazorResolveTagHelpers"
     Inputs="$(MSBuildAllProjects);$(_RazorGenerateHashFile);$(_RazorTagHelperOutputCache);@(RazorGenerate)"
-    Outputs="@(_RazorGenerateOutput)">
+    Outputs="@(_RazorGenerateOutput)"
+    Condition="'@(RazorGenerate)'!= ''">
 
     <RemoveDir
       Directories="$(RazorGenerateOutputPath)"
@@ -142,14 +155,22 @@
     </ItemGroup>
   </Target>
 
-  <Target Name="_RazorAddBuiltProjectOutputGroupOutput" Condition="'$(RazorCompileOnBuild)' == 'true'" BeforeTargets="BuiltProjectOutputGroup">
-    <ItemGroup>
+  <Target 
+    Name="_RazorAddBuiltProjectOutputGroupOutput"
+    DependsOnTargets="RazorResolveGenerateInputs"
+    BeforeTargets="BuiltProjectOutputGroup">
+
+    <ItemGroup Condition="'@(RazorGenerate)'!= '' and '$(RazorCompileOnBuild)' == 'true'">
       <BuiltProjectOutputGroupOutput Include="@(RazorIntermediateAssembly)" FinalOutputPath="$(Outdir)$(RazorTargetName).dll" />
     </ItemGroup>
+    
   </Target>
 
-  <Target Name="_RazorGetCopyToOutputDirectoryItems">
-    <ItemGroup>
+  <Target 
+    Name="_RazorGetCopyToOutputDirectoryItems" 
+    DependsOnTargets="RazorResolveGenerateInputs">
+
+    <ItemGroup Condition="'@(RazorGenerate)'!= '' and '$(RazorCompileOnBuild)' == 'true'">
       <AllItemsFullPathWithTargetPath Include="@(RazorIntermediateAssembly->'%(FullPath)')">
         <TargetPath>%(Filename)%(Extension)</TargetPath>
         <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
@@ -159,6 +180,7 @@
         <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       </AllItemsFullPathWithTargetPath>
     </ItemGroup>
+
   </Target>
 
   <Target Name="_RazorCopyFilesToOutputDirectory">

test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/Assert.cs

@@ -133,10 +133,18 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
 
             directoryPath = Path.Combine(result.Project.DirectoryPath, directoryPath);
 
-            var files = Directory.GetFiles(directoryPath, searchPattern, SearchOption.AllDirectories);
-            if (files.Length != expected)
+            if (Directory.Exists(directoryPath))
             {
-                throw new FileCountException(result, expected, directoryPath, searchPattern, files);
+                var files = Directory.GetFiles(directoryPath, searchPattern, SearchOption.AllDirectories);
+                if (files.Length != expected)
+                {
+                    throw new FileCountException(result, expected, directoryPath, searchPattern, files);
+                }
+            }
+            else if (expected > 0)
+            {
+                // directory doesn't exist, that's OK if we expected to find nothing.
+                throw new FileCountException(result, expected, directoryPath, searchPattern, Array.Empty<string>());
             }
         }
 

test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/BuildIntegrationTest.cs

@@ -41,6 +41,21 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
             }
         }
 
+        [Fact]
+        [InitializeTestProject("SimpleMvc")]
+        public async Task Build_SimpleMvc_NoopsWithNoFiles()
+        {
+            Directory.Delete(Path.Combine(Project.DirectoryPath, "Views"), recursive: true);
+
+            var result = await DotnetMSBuild("Build", "/p:RazorCompileOnBuild=true");
+
+            Assert.BuildPassed(result);
+            Assert.FileExists(result, OutputPath, "SimpleMvc.dll");
+            Assert.FileExists(result, OutputPath, "SimpleMvc.pdb");
+            Assert.FileDoesNotExist(result, OutputPath, "SimpleMvc.PrecompiledViews.dll");
+            Assert.FileDoesNotExist(result, OutputPath, "SimpleMvc.PrecompiledViews.pdb");
+        }
+
         [Fact]
         [InitializeTestProject("SimpleMvc")]
         public async Task Build_ErrorInGeneratedCode_ReportsMSBuildError()

test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/PackIntegrationTest.cs

@@ -11,7 +11,7 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
     {
         [Fact]
         [InitializeTestProject("ClassLibrary")]
-        public async Task Pack_Wortks_IncludesRazorAssembly()
+        public async Task Pack_Works_IncludesRazorAssembly()
         {
             var result = await DotnetMSBuild("Pack", "/p:RazorCompileOnBuild=true");
 

test/Microsoft.AspNetCore.Razor.Design.Test/IntegrationTests/RazorGenerateIntegrationTest.cs

@@ -178,5 +178,25 @@ namespace Microsoft.AspNetCore.Razor.Design.IntegrationTests
             Assert.BuildPassed(result);
             Assert.FileDoesNotExist(result, generatedFile);
         }
+
+        [Fact]
+        [InitializeTestProject("SimpleMvc")]
+        public async Task RazorGenerate_Noops_WithNoFiles()
+        {
+            Directory.Delete(Path.Combine(Project.DirectoryPath, "Views"), recursive: true);
+
+            var result = await DotnetMSBuild(RazorGenerateTarget);
+
+            Assert.BuildPassed(result);
+
+            // We shouldn't need to look for tag helpers
+            Assert.FileDoesNotExist(result, Path.Combine(IntermediateOutputPath, "SimpleMvc.TagHelpers.input.cache"));
+            Assert.FileDoesNotExist(result, Path.Combine(IntermediateOutputPath, "SimpleMvc.TagHelpers.output.cache"));
+
+            // We shouldn't need to hash the files
+            Assert.FileDoesNotExist(result, Path.Combine(IntermediateOutputPath, "SimpleMvc.RazorCoreGenerate.cache"));
+            
+            Assert.FileCountEquals(result, 0, RazorIntermediateOutputPath, "*.cs");
+        }
     }
 }

test/testapps/ClassLibrary/ClassLibrary.csproj

@@ -10,7 +10,9 @@
   </ItemGroup>
 
   <ItemGroup>
-    <Content Include="**\*.cshtml"/>
+    <Content Include="**\*.cshtml">
+      <Pack>false</Pack>
+    </Content>
   </ItemGroup>
   
   <ItemGroup Condition="'$(BinariesRoot)'!=''">