Fix 1023500: When saving new document, tab title doesn't update

Main problem was that `IsNewDocument = false;` is called after `FilePath` is updated(which calls SetTitleEvent) which means logic for assigning untitled name was executed instead setting to `controller.DocumentTitle`, by moving code to `DocumentManager` we achieve following things:
1) Move logic specific to FileDocumentController out of SdiWorkspaceWindow.cs
2) Simplify logic in SdiWorkspaceWindow.cs(removal of `myUntitledTitle`)
3) And by moving logic of creating unique file name closer to start of document creation reduce change of bugs and code complexity that has to deal with file name change in middle of creation
Also added unit test for new code in DocumentManager

Author: DavidKarlas

main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui.Documents/DocumentManager.cs

@@ -178,8 +178,31 @@ public Task<Document> NewDocument (string defaultName, string mimeType, string c
 			return NewDocument (defaultName, mimeType, ms);
 		}
 
+		internal string GetUniqueFileName (FilePath fileName)
+		{
+			string baseName = fileName.FileNameWithoutExtension;
+			int number = 1;
+			bool found = true;
+			var uniqueFileName = baseName + fileName.Extension;
+			while (found) {
+				found = false;
+				foreach (var document in Documents) {
+					string existingFileName = document.Name;
+					if (existingFileName == uniqueFileName) {
+						uniqueFileName = baseName + number + fileName.Extension;
+						found = true;
+						++number;
+						break;
+					}
+				}
+			}
+			return uniqueFileName;
+		}
+
 		public async Task<Document> NewDocument (string defaultName, string mimeType, Stream content)
 		{
+			defaultName = GetUniqueFileName (defaultName);
+
 			var fileDescriptor = new FileDescriptor (defaultName, mimeType, content, null);
 
 			var documentControllerService = await ServiceProvider.GetService<DocumentControllerService> ();

main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui.Shell/DefaultWorkbench.cs

@@ -1050,27 +1050,6 @@ internal void OnTabsReordered (DockNotebookTab widget, int oldPlacement, int new
 			WindowReordered?.Invoke (this, new WindowReorderedEventArgs { OldPosition = oldPlacement, NewPosition = newPlacement });
 		}
 
-		internal string GetUniqueTabName (FilePath fileName)
-		{
-			string baseName = fileName.FileNameWithoutExtension;
-			int number = 1;
-			bool found = true;
-			var myUntitledTitle = baseName + fileName.Extension;
-			while (found) {
-				found = false;
-				foreach (var window in viewContentCollection) {
-					string title = window.Title;
-					if (title == myUntitledTitle) {
-						myUntitledTitle = baseName + number + fileName.Extension;
-						found = true;
-						++number;
-						break;
-					}
-				}
-			}
-			return myUntitledTitle;
-		}
-
 		public event EventHandler<WindowReorderedEventArgs> WindowReordered;
 
 

main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui.Shell/SdiWorkspaceWindow.cs

@@ -43,7 +43,6 @@ internal class SdiWorkspaceWindow : EventBox, IWorkbenchWindow, ICommandDelegato
 		DockNotebookTab tab;
 		DockNotebook tabControl;
 
-		string myUntitledTitle;
 		string titleHolder = "";
 
 		bool showNotification;
@@ -270,13 +269,7 @@ void SetTitleEvent ()
 			if (controller == null)
 				return;
 
-			string newTitle;
-			if (controller.IsNewDocument && controller is FileDocumentController fileController) {
-				if (myUntitledTitle == null)
-					myUntitledTitle = workbench.GetUniqueTabName (fileController.FilePath);
-				newTitle = myUntitledTitle;
-			} else
-				newTitle = controller.DocumentTitle;
+			var newTitle = controller.DocumentTitle;
 
 			if (newTitle != Title)
 				Title = newTitle;

main/tests/Ide.Tests/MonoDevelop.Ide.Gui.Documents/DocumentManagerTests.cs

@@ -31,6 +31,7 @@
 using IdeUnitTests;
 using MonoDevelop.Components;
 using MonoDevelop.Core;
+using MonoDevelop.Ide.Fonts;
 using MonoDevelop.Ide.Gui.Shell;
 using MonoDevelop.Ide.TypeSystem;
 using MonoDevelop.Projects;
@@ -39,7 +40,8 @@
 
 namespace MonoDevelop.Ide.Gui.Documents
 {
-	[RequireService(typeof(TypeSystemService))]
+	[RequireService (typeof (TypeSystemService))]
+	[RequireService (typeof (FontService))]
 	public class DocumentManagerTests : TestBase
 	{
 //		BasicServiceProvider serviceProvider;
@@ -828,6 +830,15 @@ public async Task RunWhenContentAddedForSlowView()
 			Assert.AreEqual (1, contentAddedEvents);
 			Assert.IsNotNull (doc.GetContent<SomeContent> ());
 		}
+
+		[Test]
+		public async Task NewDocumentUniqueFileName()
+		{
+			const string newName = "Untitled";
+			var doc = await documentManager.NewDocument (newName, "text/plain", "");
+			var doc2 = await documentManager.NewDocument (newName, "text/plain", "");
+			Assert.AreNotEqual (doc.FileName, doc2.FileName);
+		}
 	}
 
 	class TestController: DocumentController