Ensure reference isolation

* Use TestOnly.props only for test projects
* Move analyzer references from BuildOnly.props to General.props
* Remove BuildOnly.props as it contains unused references

.gitignore

@@ -170,8 +170,8 @@ packages
 # NuGet v3's project.json files produces more ignoreable files
 *.nuget.props
 *.nuget.targets
-!src/Packages
-!eng/Packages
+!src/[Pp]ackages
+!eng/[Pp]ackages
 
 # Microsoft Azure Build Output
 csx/

Directory.Packages.props

@@ -1,6 +1,4 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <Import Project="$(MSBuildThisFileDirectory)\eng\Packages\BuildOnly.props" />
-  <Import Project="$(MSBuildThisFileDirectory)\eng\Packages\General.props" />
-  <Import Project="$(MSBuildThisFileDirectory)\eng\Packages\TestOnly.props" />
+  <Import Project="$(MSBuildThisFileDirectory)\eng\packages\General.props" />
 </Project>

bench/Directory.Build.props

@@ -1,4 +1,6 @@
 <Project>
+  <Import Project="$(MSBuildThisFileDirectory)\..\eng\packages\TestOnly.props" />
+
   <PropertyGroup>
     <GenerateDocumentationFile Condition="'$(GenerateDocumentationFile)' == ''">false</GenerateDocumentationFile>
   </PropertyGroup>

eng/build.proj

@@ -1,12 +1,12 @@
 <Project Sdk="Microsoft.Build.Traversal">
   <ItemGroup>
-      <!-- We recursively add all of the projects inside the src directory, except for the exclusions above -->
-      <_ProjectsToBuild Include="$(MSBuildThisFileDirectory)..\src\**\*.csproj" Exclude="@(_ProjectsToExclude)" />
-      <!-- We recursively add all of the test projects -->
-      <_ProjectsToBuild Include="$(MSBuildThisFileDirectory)..\test\**\*.csproj" />
-      <_ProjectsToBuild Include="$(MSBuildThisFileDirectory)..\bench\**\*.csproj" />
-      
-      <!-- Add all the projects we want to build as project references, so the traversal SDK can build them -->
-      <ProjectReference Include="@(_ProjectsToBuild)" />
+    <!-- We recursively add all of the projects inside the src directory, except for the exclusions above -->
+    <_ProjectsToBuild Include="$(MSBuildThisFileDirectory)..\src\**\*.csproj" Exclude="@(_ProjectsToExclude)" />
+    <!-- We recursively add all of the test projects -->
+    <_ProjectsToBuild Include="$(MSBuildThisFileDirectory)..\test\**\*.csproj" />
+    <_ProjectsToBuild Include="$(MSBuildThisFileDirectory)..\bench\**\*.csproj" />
+
+    <!-- Add all the projects we want to build as project references, so the traversal SDK can build them -->
+    <ProjectReference Include="@(_ProjectsToBuild)" />
   </ItemGroup>
 </Project>

eng/Packages/General.props → eng/packages/General.props

@@ -66,6 +66,12 @@
     <PackageVersion Include="YamlDotNet" Version="13.1.1" />
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageVersion Include="Microsoft.VisualStudio.Threading.Analyzers" Version="17.5.22" />
+    <PackageVersion Include="SonarAnalyzer.CSharp" Version="8.52.0.60960" />
+    <PackageVersion Include="StyleCop.Analyzers.Unstable" Version="1.2.0.435" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(TargetFramework)' == 'net462'">
     <PackageVersion Include="Microsoft.AspNetCore.Http.Features" Version="2.2.0" />
     <PackageVersion Include="Microsoft.AspNetCore.Http" Version="2.2.2" />

test/Directory.Build.props

@@ -1,4 +1,6 @@
 <Project>
+  <Import Project="$(MSBuildThisFileDirectory)\..\eng\packages\TestOnly.props" />
+
   <PropertyGroup>
     <GenerateDocumentationFile Condition="'$(GenerateDocumentationFile)' == ''">false</GenerateDocumentationFile>
   </PropertyGroup>