Correct validation of namespace identifier

src/Compilers/Core/Portable/InternalUtilities/UnicodeCharacterUtilities.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.Globalization;
+using System.Linq;
 
 namespace Roslyn.Utilities
 {
@@ -109,6 +110,19 @@ public static bool IsValidIdentifier(string name)
             return true;
         }
 
+        /// <summary>
+        /// Returns true if every identifier in a namespace is valid using <see cref="IsValidIdentifier(string)"/>
+        /// </summary>
+        public static bool IsValidNamespace(string @namespace)
+        {
+            if (string.IsNullOrEmpty(@namespace))
+            {
+                return false;
+            }
+
+            return @namespace.Split('.').All(IsValidIdentifier);
+        }
+
         private static bool IsLetterChar(UnicodeCategory cat)
         {
             // letter-character:

src/EditorFeatures/TestUtilities/MoveToNamespace/TestMoveToNamespaceOptionsService.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.
 
-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-
 extern alias WORKSPACES;
 
 using System;
+using System.Collections.Immutable;
 using System.ComponentModel.Composition;
 using System.Threading;
 using System.Threading.Tasks;
@@ -25,7 +24,7 @@ public TestMoveToNamespaceOptionsService()
         {
         }
 
-        public Task<MoveToNamespaceOptionsResult> GetChangeNamespaceOptionsAsync(ISyntaxFactsService syntaxFactsService, INotificationService notificationService, string defaultNamespace, CancellationToken cancellationToken)
+        public Task<MoveToNamespaceOptionsResult> GetChangeNamespaceOptionsAsync(string defaultNamespace, ImmutableArray<string> availableNamespaces, CancellationToken cancellationToken)
         {
             throw new NotImplementedException();
         }

src/Features/Core/Portable/MoveToNamespace/AbstractMoveToNamespaceService.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.Immutable;
 using System.Linq;
+using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.ChangeNamespace;
@@ -125,8 +127,6 @@ private bool ContainsNamespaceDeclaration(SyntaxNode node)
                 .Select(n => n.ToDisplayString(QualifiedNamespaceFormat));
 
             return await _moveToNamespaceOptionsService.GetChangeNamespaceOptionsAsync(
-                syntaxFactsService,
-                notificationService,
                 defaultNamespace,
                 namespaces.ToImmutableArray(),
                 cancellationToken).ConfigureAwait(false);

src/Features/Core/Portable/MoveToNamespace/IMoveToNamespaceOptionsService.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.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Host;
-using Microsoft.CodeAnalysis.LanguageServices;
-using Microsoft.CodeAnalysis.Notification;
 
 namespace Microsoft.CodeAnalysis.MoveToNamespace
 {
     internal interface IMoveToNamespaceOptionsService : IWorkspaceService
     {
         Task<MoveToNamespaceOptionsResult> GetChangeNamespaceOptionsAsync(
-            ISyntaxFactsService syntaxFactsService,
-            INotificationService notificationService,
             string defaultNamespace,
             ImmutableArray<string> availableNamespaces,
             CancellationToken cancellationToken);

src/VisualStudio/Core/Def/Implementation/MoveToNamespace/MoveToNamespaceDialogViewModel.cs

@@ -5,13 +5,14 @@
 using Microsoft.VisualStudio.Language.Intellisense;
 using Microsoft.VisualStudio.LanguageServices.Implementation.Utilities;
 using Microsoft.VisualStudio.Imaging;
+using Microsoft.CodeAnalysis.MoveToNamespace;
+using Roslyn.Utilities;
 
 namespace Microsoft.VisualStudio.LanguageServices.Implementation.MoveToNamespace
 {
     class MoveToNamespaceDialogViewModel : AbstractNotifyPropertyChanged
     {
         public MoveToNamespaceDialogViewModel(
-            IGlyphService glyphService,
             string defaultNamespace,
             ImmutableArray<string> availableNamespaces)
         {
@@ -34,7 +35,7 @@ private void MoveToNamespaceDialogViewModel_PropertyChanged(object sender, Syste
         public void OnNamespaceUpdated()
         {
             var isNewNamespace = !AvailableNamespaces.Contains(NamespaceName);
-            var isValidName = !isNewNamespace || IsValidNamespace(NamespaceName);
+            var isValidName = !isNewNamespace || UnicodeCharacterUtilities.IsValidNamespace(NamespaceName);
 
             if (isNewNamespace && isValidName)
             {
@@ -57,11 +58,6 @@ public void OnNamespaceUpdated()
             }
         }
 
-        private static bool IsValidNamespace(string @namespace)
-        {
-            return !@namespace.Contains(" ");
-        }
-
         private string _namespaceName;
         public string NamespaceName
         {

src/VisualStudio/Core/Def/Implementation/MoveToNamespace/VisualStudioMoveToNamespaceOptionsService.cs

@@ -29,8 +29,6 @@ public VisualStudioMoveToNamespaceOptionsService(IGlyphService glyphService, ITh
         }
 
         public async Task<MoveToNamespaceOptionsResult> GetChangeNamespaceOptionsAsync(
-            ISyntaxFactsService syntaxFactsService,
-            INotificationService notificationService,
             string defaultNamespace,
             ImmutableArray<string> availableNamespaces,
             CancellationToken cancellationToken)
@@ -39,7 +37,6 @@ public VisualStudioMoveToNamespaceOptionsService(IGlyphService glyphService, ITh
             cancellationToken.ThrowIfCancellationRequested();
 
             var viewModel = new MoveToNamespaceDialogViewModel(
-                _glyphService,
                 defaultNamespace,
                 availableNamespaces);