Break type into its own file.

src/Features/Core/Portable/AddImport/CodeActions/AssemblyReferenceCodeAction.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.Host;
+using Microsoft.CodeAnalysis.Tags;
+using Roslyn.Utilities;
+
+namespace Microsoft.CodeAnalysis.CodeFixes.AddImport
+{
+    internal abstract partial class AbstractAddImportCodeFixProvider<TSimpleNameSyntax>
+    {
+        private partial class AssemblyReference
+        {
+            private class AssemblyReferenceCodeAction : CodeAction
+            {
+                private readonly AssemblyReference _reference;
+                private readonly string _title;
+                private readonly Document _document;
+                private readonly SyntaxNode _node;
+                private readonly bool _placeSystemNamespaceFirst;
+
+                public override string Title => _title;
+
+                public override ImmutableArray<string> Tags => WellKnownTagArrays.AddReference;
+
+                private readonly Lazy<string> _lazyResolvedPath;
+
+                public AssemblyReferenceCodeAction(
+                    AssemblyReference reference,
+                    Document document,
+                    SyntaxNode node,
+                    bool placeSystemNamespaceFirst)
+                {
+                    _reference = reference;
+                    _document = document;
+                    _node = node;
+                    _placeSystemNamespaceFirst = placeSystemNamespaceFirst;
+
+                    _title = $"{reference.provider.GetDescription(reference.SearchResult.NameParts)} ({string.Format(FeaturesResources.from_0, reference._referenceAssemblyWithType.AssemblyName)})";
+                    _lazyResolvedPath = new Lazy<string>(ResolvePath);
+                }
+
+                // Adding a reference is always low priority.
+                internal override CodeActionPriority Priority => CodeActionPriority.Low;
+
+                private string ResolvePath()
+                {
+                    var assemblyResolverService = _document.Project.Solution.Workspace.Services.GetService<IFrameworkAssemblyPathResolver>();
+
+                    var packageWithType = _reference._referenceAssemblyWithType;
+                    var fullyQualifiedName = string.Join(".", packageWithType.ContainingNamespaceNames.Concat(packageWithType.TypeName));
+                    var assemblyPath = assemblyResolverService?.ResolveAssemblyPath(
+                        _document.Project.Id, packageWithType.AssemblyName, fullyQualifiedName);
+
+                    return assemblyPath;
+                }
+
+                internal override bool PerformFinalApplicabilityCheck => true;
+
+                internal override bool IsApplicable(Workspace workspace)
+                {
+                    return !string.IsNullOrWhiteSpace(_lazyResolvedPath.Value);
+                }
+
+                protected override async Task<IEnumerable<CodeActionOperation>> ComputeOperationsAsync(CancellationToken cancellationToken)
+                {
+                    var service = _document.Project.Solution.Workspace.Services.GetService<IMetadataService>();
+                    var resolvedPath = _lazyResolvedPath.Value;
+                    var reference = service.GetReference(resolvedPath, MetadataReferenceProperties.Assembly);
+
+                    // First add the "using/import" directive in the code.
+                    (SyntaxNode node, Document document) = await _reference.ReplaceNameNodeAsync(
+                        _node, _document, cancellationToken).ConfigureAwait(false);
+
+                    var newDocument = await _reference.provider.AddImportAsync(
+                        node, _reference.SearchResult.NameParts, document, _placeSystemNamespaceFirst, cancellationToken).ConfigureAwait(false);
+
+                    // Now add the actual assembly reference.
+                    var newProject = newDocument.Project;
+                    newProject = newProject.WithMetadataReferences(
+                        newProject.MetadataReferences.Concat(reference));
+
+                    var operation = new ApplyChangesOperation(newProject.Solution);
+                    return SpecializedCollections.SingletonEnumerable<CodeActionOperation>(operation);
+                }
+            }
+        }
+    }
+}
\ No newline at end of file

src/Features/Core/Portable/AddImport/References/AssemblyReference.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
-using System;
-using System.Collections.Generic;
-using System.Collections.Immutable;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeActions;
-using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.SymbolSearch;
-using Microsoft.CodeAnalysis.Tags;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CodeFixes.AddImport
 {
     internal abstract partial class AbstractAddImportCodeFixProvider<TSimpleNameSyntax>
     {
-        private class AssemblyReference : Reference
+        private partial class AssemblyReference : Reference
         {
             private readonly ReferenceAssemblyWithTypeResult _referenceAssemblyWithType;
 
@@ -46,80 +41,6 @@ public override int GetHashCode()
             {
                 return Hash.Combine(_referenceAssemblyWithType.AssemblyName, base.GetHashCode());
             }
-
-            private class AssemblyReferenceCodeAction : CodeAction
-            {
-                private readonly AssemblyReference _reference;
-                private readonly string _title;
-                private readonly Document _document;
-                private readonly SyntaxNode _node;
-                private readonly bool _placeSystemNamespaceFirst;
-
-                public override string Title => _title;
-
-                public override ImmutableArray<string> Tags => WellKnownTagArrays.AddReference;
-
-                private readonly Lazy<string> _lazyResolvedPath;
-
-                public AssemblyReferenceCodeAction(
-                    AssemblyReference reference,
-                    Document document,
-                    SyntaxNode node,
-                    bool placeSystemNamespaceFirst)
-                {
-                    _reference = reference;
-                    _document = document;
-                    _node = node;
-                    _placeSystemNamespaceFirst = placeSystemNamespaceFirst;
-
-                    _title = $"{reference.provider.GetDescription(reference.SearchResult.NameParts)} ({string.Format(FeaturesResources.from_0, reference._referenceAssemblyWithType.AssemblyName)})";
-                    _lazyResolvedPath = new Lazy<string>(ResolvePath);
-                }
-
-                // Adding a reference is always low priority.
-                internal override CodeActionPriority Priority => CodeActionPriority.Low;
-
-                private string ResolvePath()
-                {
-                    var assemblyResolverService = _document.Project.Solution.Workspace.Services.GetService<IFrameworkAssemblyPathResolver>();
-
-                    var packageWithType = _reference._referenceAssemblyWithType;
-                    var fullyQualifiedName = string.Join(".", packageWithType.ContainingNamespaceNames.Concat(packageWithType.TypeName));
-                    var assemblyPath = assemblyResolverService?.ResolveAssemblyPath(
-                        _document.Project.Id, packageWithType.AssemblyName, fullyQualifiedName);
-
-                    return assemblyPath;
-                }
-
-                internal override bool PerformFinalApplicabilityCheck => true;
-
-                internal override bool IsApplicable(Workspace workspace)
-                {
-                    return !string.IsNullOrWhiteSpace(_lazyResolvedPath.Value);
-                }
-
-                protected override async Task<IEnumerable<CodeActionOperation>> ComputeOperationsAsync(CancellationToken cancellationToken)
-                {
-                    var service = _document.Project.Solution.Workspace.Services.GetService<IMetadataService>();
-                    var resolvedPath = _lazyResolvedPath.Value;
-                    var reference = service.GetReference(resolvedPath, MetadataReferenceProperties.Assembly);
-
-                    // First add the "using/import" directive in the code.
-                    (SyntaxNode node, Document document) = await _reference.ReplaceNameNodeAsync(
-                        _node, _document, cancellationToken).ConfigureAwait(false);
-
-                    var newDocument = await _reference.provider.AddImportAsync(
-                        node, _reference.SearchResult.NameParts, document, _placeSystemNamespaceFirst, cancellationToken).ConfigureAwait(false);
-
-                    // Now add the actual assembly reference.
-                    var newProject = newDocument.Project;
-                    newProject = newProject.WithMetadataReferences(
-                        newProject.MetadataReferences.Concat(reference));
-
-                    var operation = new ApplyChangesOperation(newProject.Solution);
-                    return SpecializedCollections.SingletonEnumerable<CodeActionOperation>(operation);
-                }
-            }
         }
     }
 }
\ No newline at end of file

src/Features/Core/Portable/Features.csproj

@@ -100,6 +100,7 @@
     <Compile Include="..\..\..\Compilers\Shared\DesktopShim.cs">
       <Link>Shared\Utilities\DesktopShim.cs</Link>
     </Compile>
+    <Compile Include="AddImport\CodeActions\AssemblyReferenceCodeAction.cs" />
     <Compile Include="AddImport\SearchScopes\AllSymbolsProjectSearchScope.cs" />
     <Compile Include="AddImport\SearchScopes\MetadataSymbolsSearchScope.cs" />
     <Compile Include="AddImport\SearchScopes\ProjectSearchScope.cs" />