Do not re-open an already currently opened workspace

Fixes #5630

- fixes an issue that allows users to open a workspace
that is currently opened. If the user had the preference
`"workspace.preserveWindow"` set to `false` it would open
an identical workspace in a new tab, and if it was set to
`true` it would reload the workspace. Instead, an additional
check is performed to determine if the current workspace and
the new destination are equal, and if they are a NOOP is
instead performed by returning `undefined`.

Signed-off-by: Vincent Fugnitto <[email protected]>

packages/workspace/src/browser/workspace-frontend-contribution.ts

@@ -22,7 +22,7 @@ import {
     ConfirmDialog, KeybindingRegistry, KeybindingContribution, CommonCommands
 } from '@theia/core/lib/browser';
 import { FileDialogService, OpenFileDialogProps, FileDialogTreeFilters } from '@theia/filesystem/lib/browser';
-import { FileSystem } from '@theia/filesystem/lib/common';
+import { FileSystem, FileStat } from '@theia/filesystem/lib/common';
 import { ContextKeyService } from '@theia/core/lib/browser/context-key-service';
 import { WorkspaceService } from './workspace-service';
 import { THEIA_EXT, VSCODE_EXT } from '../common';
@@ -181,6 +181,10 @@ export class WorkspaceFrontendContribution implements CommandContribution, Keybi
         }, rootStat);
         if (destinationUri) {
             const destination = await this.fileSystem.getFileStat(destinationUri.toString());
+            // If the current workspace and destination are equal, do nothing.
+            if (FileStat.equals(destination, this.workspaceService.workspace)) {
+                return undefined;
+            }
             if (destination) {
                 if (destination.isDirectory) {
                     this.workspaceService.open(destinationUri);