Support adding PackageReferences to CPS projects

Add APIs to allow integration tests to add PackageReferences to CPS projects.

build/Targets/Packages.props

@@ -89,6 +89,7 @@
     <MicrosoftVisualStudioProgressionCodeSchemaVersion>15.0.26507-alpha</MicrosoftVisualStudioProgressionCodeSchemaVersion>
     <MicrosoftVisualStudioProgressionCommonVersion>15.0.26507-alpha</MicrosoftVisualStudioProgressionCommonVersion>
     <MicrosoftVisualStudioProgressionInterfacesVersion>15.0.26507-alpha</MicrosoftVisualStudioProgressionInterfacesVersion>
+    <MicrosoftVisualStudioProjectSystemVersion>15.0.751</MicrosoftVisualStudioProjectSystemVersion>
     <MicrosoftVisualStudioQualityToolsUnitTestFrameworkVersion>10.0.0.0-alpha</MicrosoftVisualStudioQualityToolsUnitTestFrameworkVersion>
     <MicrosoftVisualStudioRemoteControlVersion>14.0.249-master2E2DC10C</MicrosoftVisualStudioRemoteControlVersion>
     <MicrosoftVisualStudioSetupConfigurationInteropVersion>1.3.269-rc</MicrosoftVisualStudioSetupConfigurationInteropVersion>

src/VisualStudio/IntegrationTest/TestUtilities/Common/ProjectUtilities.cs

@@ -30,4 +30,15 @@ public AssemblyReference(string name)
             Name = name;
         }
     }
+
+    public class PackageReference : Identity
+    {
+        public string Version { get; }
+
+        public PackageReference(string name, string version)
+        {
+            Name = name;
+            Version = version;
+        }
+    }
 }

src/VisualStudio/IntegrationTest/TestUtilities/InProcess/SolutionExplorer_InProc.cs

@@ -9,6 +9,7 @@
 using System.Xml.Linq;
 using EnvDTE80;
 using Microsoft.CodeAnalysis;
+using Microsoft.VisualStudio.ProjectSystem.Properties;
 using Microsoft.VisualStudio.Shell.Interop;
 using Microsoft.VisualStudio.Text.Editor;
 using Microsoft.VisualStudio.TextManager.Interop;
@@ -214,6 +215,38 @@ public void AddReference(string projectName, string fullyQualifiedAssemblyName)
             ((VSProject)project.Object).References.Add(fullyQualifiedAssemblyName);
         }
 
+        public void AddPackageReference(string projectName, string packageName, string version)
+        {
+            var project = GetProject(projectName);
+
+            if (project.Object is IVsBrowseObjectContext browseObjectContext)
+            {
+                var threadingService = browseObjectContext.UnconfiguredProject.ProjectService.Services.ThreadingPolicy;
+                var packageService = browseObjectContext.ConfiguredProject.Services.PackageReferences;
+
+                var result = threadingService.ExecuteSynchronously(async () =>
+                {
+                    return await packageService.AddAsync(packageName, version);
+                });
+            }
+        }
+
+        public void RemovePackageReference(string projectName, string packageName)
+        {
+            var project = GetProject(projectName);
+
+            if (project.Object is IVsBrowseObjectContext browseObjectContext)
+            {
+                var threadingService = browseObjectContext.UnconfiguredProject.ProjectService.Services.ThreadingPolicy;
+                var packageService = browseObjectContext.ConfiguredProject.Services.PackageReferences;
+
+                var result = threadingService.ExecuteSynchronously(async () =>
+                {
+                    return await packageService.RemoveAsync(packageName);
+                });
+            }
+        }
+
         public void RemoveProjectReference(string projectName, string projectReferenceName)
         {
             var project = GetProject(projectName);

src/VisualStudio/IntegrationTest/TestUtilities/OutOfProcess/SolutionExplorer_OutOfProc.cs

@@ -69,6 +69,20 @@ public void RemoveMetadataReference(ProjectUtils.AssemblyReference assemblyName,
             _instance.Workspace.WaitForAsyncOperations(FeatureAttribute.Workspace);
         }
 
+        /// <summary>
+        /// Add a PackageReference to the specified project. Generally this should be followed up by
+        /// a call to <see cref="RestoreNuGetPackages"/>.
+        /// </summary>
+        public void AddPackageReference(ProjectUtils.Project project, ProjectUtils.PackageReference package)
+            => _inProc.AddPackageReference(project.Name, package.Name, package.Version);
+
+        /// <summary>
+        /// Remove a PackageReference from the specified project. Generally this should be followed up by
+        /// a call to <see cref="RestoreNuGetPackages"/>.
+        /// </summary>
+        public void RemovePackageReference(ProjectUtils.Project project, ProjectUtils.PackageReference package)
+            => _inProc.RemovePackageReference(project.Name, package.Name);
+
         public void CleanUpOpenSolution()
             => _inProc.CleanUpOpenSolution();
 

src/VisualStudio/IntegrationTest/TestUtilities/VisualStudioIntegrationTestUtilities.csproj

@@ -129,6 +129,9 @@
     <PackageReference Include="Microsoft.VisualStudio.OLE.Interop">
       <Version>$(MicrosoftVisualStudioOLEInteropVersion)</Version>
     </PackageReference>
+    <PackageReference Include="Microsoft.VisualStudio.ProjectSystem">
+      <Version>$(MicrosoftVisualStudioProjectSystemVersion)</Version>
+    </PackageReference>
     <PackageReference Include="Microsoft.VisualStudio.Setup.Configuration.Interop">
       <Version>$(MicrosoftVisualStudioSetupConfigurationInteropVersion)</Version>
     </PackageReference>