add test and fix issue with swapping folders

src/vs/workbench/api/node/extHostWorkspace.ts

@@ -59,6 +59,9 @@ class ExtHostWorkspaceImpl extends Workspace {
 			newWorkspaceFolders.push(...folders.map(({ uri, name, index }) => ({ uri: URI.revive(uri), name, index })));
 		}
 
+		// make sure to restore sort order based on index
+		newWorkspaceFolders.sort((f1, f2) => f1.index < f2.index ? -1 : 1);
+
 		const workspace = new ExtHostWorkspaceImpl(id, name, newWorkspaceFolders);
 
 		const oldRoots = oldWorkspace ? oldWorkspace.workspaceFolders.sort(ExtHostWorkspaceImpl.compareWorkspaceFolderByUri) : [];
@@ -73,7 +76,11 @@ class ExtHostWorkspaceImpl extends Workspace {
 		return isFolderEqual(a.uri, b.uri) ? 0 : compare(a.uri.toString(), b.uri.toString());
 	}
 
-	static compareWorkspaceFolderByUriAndName(a: vscode.WorkspaceFolder, b: vscode.WorkspaceFolder): number {
+	static compareWorkspaceFolderByUriAndNameAndIndex(a: vscode.WorkspaceFolder, b: vscode.WorkspaceFolder): number {
+		if (a.index !== b.index) {
+			return a.index < b.index ? -1 : 1;
+		}
+
 		return isFolderEqual(a.uri, b.uri) ? compare(a.name, b.name) : compare(a.uri.toString(), b.uri.toString());
 	}
 
@@ -175,7 +182,7 @@ export class ExtHostWorkspace implements ExtHostWorkspaceShape {
 		newWorkspaceFolders.splice(index, deleteCount, ...validatedDistinctWorkspaceFoldersToAdd.map((f, index) => ({ uri: f.uri, name: f.name || basenameOrAuthority(f.uri), index })));
 		const oldRoots = currentWorkspaceFolders.sort(ExtHostWorkspaceImpl.compareWorkspaceFolderByUri);
 		const newRoots = newWorkspaceFolders.sort(ExtHostWorkspaceImpl.compareWorkspaceFolderByUri);
-		const { added, removed } = delta(oldRoots, newRoots, ExtHostWorkspaceImpl.compareWorkspaceFolderByUriAndName);
+		const { added, removed } = delta(oldRoots, newRoots, ExtHostWorkspaceImpl.compareWorkspaceFolderByUriAndNameAndIndex);
 		if (added.length === 0 && removed.length === 0) {
 			return false; // nothing actually changed
 		}

src/vs/workbench/test/electron-browser/api/extHostWorkspace.test.ts

@@ -373,6 +373,8 @@ suite('ExtHostWorkspace', function () {
 		assert.equal(ws.workspace.folders[1].uri.toString(), URI.parse('foo:bar1').toString());
 		assert.equal(ws.workspace.folders[0].name, 'renamed 1');
 		assert.equal(ws.workspace.folders[1].name, 'renamed 2');
+		assert.equal(ws.getWorkspaceFolders()[0].name, 'renamed 1');
+		assert.equal(ws.getWorkspaceFolders()[1].name, 'renamed 2');
 
 		gotEvent = false;
 		sub = ws.onDidChangeWorkspace(e => {
@@ -389,6 +391,10 @@ suite('ExtHostWorkspace', function () {
 		sub.dispose();
 		assert.equal(ws.getWorkspaceFolders()[0], firstAddedFolder); // verify object is still live
 		assert.equal(ws.getWorkspaceFolders()[1], secondAddedFolder); // verify object is still live
+		assert.equal(ws.workspace.folders[0].name, 'renamed 1');
+		assert.equal(ws.workspace.folders[1].name, 'renamed 2');
+		assert.equal(ws.getWorkspaceFolders()[0].name, 'renamed 1');
+		assert.equal(ws.getWorkspaceFolders()[1].name, 'renamed 2');
 
 		//
 		// Add and remove folders
@@ -422,6 +428,36 @@ suite('ExtHostWorkspace', function () {
 		assert.equal(ws.getWorkspaceFolders()[0], fourthAddedFolder); // verify object is still live
 		assert.equal(ws.getWorkspaceFolders()[1], fifthAddedFolder); // verify object is still live
 
+		//
+		// Swap folders
+		//
+
+		assert.equal(true, ws.updateWorkspaceFolders('ext', 0, 2, aWorkspaceFolderData(URI.parse('foo:bar4'), 0), aWorkspaceFolderData(URI.parse('foo:bar3'), 1)));
+		assert.equal(2, ws.workspace.folders.length);
+		assert.equal(ws.workspace.folders[0].uri.toString(), URI.parse('foo:bar4').toString());
+		assert.equal(ws.workspace.folders[1].uri.toString(), URI.parse('foo:bar3').toString());
+
+		assert.equal(ws.getWorkspaceFolders()[0], fifthAddedFolder); // verify object is still live
+		assert.equal(ws.getWorkspaceFolders()[1], fourthAddedFolder); // verify object is still live
+
+		gotEvent = false;
+		sub = ws.onDidChangeWorkspace(e => {
+			try {
+				assert.equal(e.added.length, 0);
+				assert.equal(e.removed.length, 0);
+				gotEvent = true;
+			} catch (error) {
+				finish(error);
+			}
+		});
+		ws.$acceptWorkspaceData({ id: 'foo', name: 'Test', folders: [aWorkspaceFolderData(URI.parse('foo:bar4'), 0), aWorkspaceFolderData(URI.parse('foo:bar3'), 1)] }); // simulate acknowledgement from main side
+		assert.equal(gotEvent, true);
+		sub.dispose();
+		assert.equal(ws.getWorkspaceFolders()[0], fifthAddedFolder); // verify object is still live
+		assert.equal(ws.getWorkspaceFolders()[1], fourthAddedFolder); // verify object is still live
+		assert.equal(fifthAddedFolder.index, 0);
+		assert.equal(fourthAddedFolder.index, 1);
+
 		finish();
 	});