Implement VS Reference.SourceProject.

src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/Reference.cs

@@ -26,5 +26,15 @@ namespace ICSharpCode.PackageManagement.EnvDTE
 			project.RemoveReference(referenceProjectItem);
 			project.Save();
 		}
+		
+		public Project SourceProject {
+			get {
+				var projectReference = referenceProjectItem as ProjectReferenceProjectItem;
+				if (projectReference != null) {
+					return new Project(projectReference.ReferencedProject as MSBuildBasedProject);
+				}
+				return null;
+			}
+		}
 	}
 }

src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/ReferenceTests.cs

@@ -4,6 +4,7 @@
 using System;
 using ICSharpCode.PackageManagement.Design;
 using ICSharpCode.PackageManagement.EnvDTE;
+using ICSharpCode.SharpDevelop.Project;
 using NUnit.Framework;
 using PackageManagement.Tests.Helpers;
 
@@ -21,11 +22,27 @@ namespace PackageManagement.Tests.EnvDTE
 		{
 			project = new TestableDTEProject();
 			msbuildProject = project.TestableProject;
-			var referenceProjectItem = msbuildProject.AddReference(name);
+			ReferenceProjectItem referenceProjectItem = msbuildProject.AddReference(name);
 			fakeProjectService = project.FakeProjectService;
+			CreateReference(project, referenceProjectItem);
+		}
+		
+		void CreateReference(Project project, ReferenceProjectItem referenceProjectItem)
+		{
 			reference = new Reference(project, referenceProjectItem);
 		}
 		
+		TestableProject CreateProjectReference()
+		{
+			project = new TestableDTEProject();
+			msbuildProject = project.TestableProject;
+			TestableProject referencedProject = ProjectHelper.CreateTestProject();
+			ProjectReferenceProjectItem referenceProjectItem = msbuildProject.AddProjectReference(referencedProject);
+			fakeProjectService = project.FakeProjectService;
+			CreateReference(project, referenceProjectItem);
+			return referencedProject;
+		}
+		
 		[Test]
 		public void Name_ReferenceNameIsSystemXml_ReturnsSystemXml()
 		{
@@ -58,5 +75,26 @@ namespace PackageManagement.Tests.EnvDTE
 			
 			Assert.IsTrue(saved);
 		}
+		
+		[Test]
+		public void SourceProject_SystemXmlReference_ReturnsNull()
+		{
+			CreateReference("System.Xml");
+			
+			Project project = reference.SourceProject;
+			
+			Assert.IsNull(project);
+		}
+		
+		[Test]
+		public void SourceProject_ReferenceIsProjectReference_ReturnsReferencedProject()
+		{
+			TestableProject referencedProject = CreateProjectReference();
+			referencedProject.FileName = @"d:\projects\referencedproject.csproj";
+			
+			Project project = reference.SourceProject;
+			
+			Assert.AreEqual(@"d:\projects\referencedproject.csproj", project.FileName);
+		}
 	}
 }

src/AddIns/Misc/PackageManagement/Test/Src/Helpers/TestableProject.cs

@@ -49,6 +49,13 @@ namespace PackageManagement.Tests.Helpers
 			return referenceProjectItem;
 		}
 		
+		public ProjectReferenceProjectItem AddProjectReference(IProject referencedProject)
+		{
+			var referenceProjectItem = new ProjectReferenceProjectItem(this, referencedProject);
+			ProjectService.AddProjectItem(this, referenceProjectItem);
+			return referenceProjectItem;
+		}
+		
 		public FileProjectItem AddFile(string include)
 		{
 			var fileProjectItem = new FileProjectItem(this, ItemType.Compile, include);