Expose Imports in IProjectFile (#615)

* Simple implementation to expose Imports in IProjectFile

* Change to use a custom Collection for Imports

* Add a null check to fix tests

* Add implementation for CopyTo

* Changing GetEnumerator impl to fix tests

src/common/Microsoft.DotNet.UpgradeAssistant.Abstractions/IProjectFile.cs

@@ -41,6 +41,6 @@ namespace Microsoft.DotNet.UpgradeAssistant
 
         void SetTFM(TargetFrameworkMoniker targetTFM);
 
-        IEnumerable<string> Imports { get; }
+        ICollection<string> Imports { get; }
     }
 }

src/components/Microsoft.DotNet.UpgradeAssistant.MSBuild/ComponentIdentifier.cs

@@ -101,7 +101,7 @@ namespace Microsoft.DotNet.UpgradeAssistant.MSBuild
             // Check imports and references
             var references = project.References.Select(r => r.Name);
 
-            if (file.Imports.Contains(MSBuildConstants.WebApplicationTargets, StringComparer.OrdinalIgnoreCase) ||
+            if ((file.Imports != null && file.Imports.Contains(MSBuildConstants.WebApplicationTargets, StringComparer.OrdinalIgnoreCase)) ||
                 references.Any(r => MSBuildConstants.WebReferences.Contains(r, StringComparer.OrdinalIgnoreCase)))
             {
                 components |= ProjectComponents.AspNet;

src/components/Microsoft.DotNet.UpgradeAssistant.MSBuild/ImportsCollection.cs

@@ -0,0 +1,86 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using Microsoft.Build.Construction;
+
+namespace Microsoft.DotNet.UpgradeAssistant.MSBuild
+{
+    public class ImportsCollection : ICollection<string>
+    {
+        private readonly ProjectRootElement _projectRoot;
+
+        public ImportsCollection(ProjectRootElement projectRoot)
+        {
+            _projectRoot = projectRoot;
+        }
+
+        public bool Contains(string item)
+        {
+            if (_projectRoot.Imports.Any(p => item.Equals(p.Project, StringComparison.Ordinal)))
+            {
+                return true;
+            }
+
+            return false;
+        }
+
+        public void Add(string item)
+        {
+            if (!Contains(item))
+            {
+                _projectRoot.AddImport(item);
+            }
+        }
+
+        public void Clear()
+        {
+            _projectRoot.Imports.Clear();
+        }
+
+        public int Count
+        {
+            get
+            {
+                return _projectRoot.Imports.Count;
+            }
+        }
+
+        public bool IsReadOnly
+        {
+            get { return false; }
+        }
+
+        public bool Remove(string item)
+        {
+            var element = _projectRoot.Imports.FirstOrDefault(p => item.Equals(p.Project, StringComparison.Ordinal));
+
+            if (element != null)
+            {
+                element.RemoveElement();
+                return true;
+            }
+
+            return false;
+        }
+
+        public void CopyTo(string[] array, int arrayIndex)
+        {
+            ((ICollection<string>)this).CopyTo(array, arrayIndex);
+        }
+
+        public IEnumerator<string> GetEnumerator()
+        {
+            return _projectRoot.Imports.Select(p => p.Project).GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return _projectRoot.Imports.GetEnumerator();
+        }
+    }
+}

src/components/Microsoft.DotNet.UpgradeAssistant.MSBuild/MSBuildProject.File.cs

@@ -56,7 +56,7 @@ namespace Microsoft.DotNet.UpgradeAssistant.MSBuild
         public bool IsSdk =>
             ProjectRoot.Sdk is not null && ProjectRoot.Sdk.Contains(MSBuildConstants.DefaultSDK, StringComparison.OrdinalIgnoreCase);
 
-        public IEnumerable<string> Imports => ProjectRoot.Imports.Select(p => Path.GetFileName(p.Project));
+        public ICollection<string> Imports => new ImportsCollection(ProjectRoot);
 
         public void SetTFM(TargetFrameworkMoniker tfm) => new TargetFrameworkMonikerCollection(this, _comparer).SetTargetFramework(tfm);
 

tests/tool/Integration.Tests/IntegrationScenarios/WpfSample/csharp/Original/NuGet.Config

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
   <packageSources>
+    <clear />
     <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
   </packageSources>
 </configuration>

tests/tool/Integration.Tests/IntegrationScenarios/WpfSample/csharp/Upgraded/NuGet.Config

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
   <packageSources>
+    <clear />
     <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
   </packageSources>
 </configuration>