Re microsoft/vscode-github-issue-notebooks#26. test for regression.

extensions/vscode-notebook-tests/src/notebook.test.ts

@@ -320,3 +320,15 @@ suite('notebook working copy', () => {
 		await vscode.commands.executeCommand('workbench.action.closeActiveEditor');
 	});
 });
+
+suite('regression', () => {
+	test('microsoft/vscode-github-issue-notebooks#26. Insert template cell in the new empty document', async function () {
+		const resource = vscode.Uri.parse(join(vscode.workspace.rootPath || '', './empty.vsctestnb'));
+		await vscode.commands.executeCommand('vscode.openWith', resource, 'notebookCoreTest');
+
+		await waitFor(500);
+		assert.equal(vscode.notebook.activeNotebookEditor !== undefined, true, 'notebook first');
+		assert.equal(vscode.notebook.activeNotebookEditor!.selection?.source, '');
+		assert.equal(vscode.notebook.activeNotebookEditor!.selection?.language, 'typescript');
+	});
+});

extensions/vscode-notebook-tests/src/notebookTestMain.ts

@@ -9,6 +9,14 @@ export function activate(context: vscode.ExtensionContext): any {
 	context.subscriptions.push(vscode.notebook.registerNotebookContentProvider('notebookCoreTest', {
 		onDidChangeNotebook: new vscode.EventEmitter<vscode.NotebookDocumentEditEvent>().event,
 		openNotebook: async (_resource: vscode.Uri) => {
+			if (_resource.path.endsWith('empty.vsctestnb')) {
+				return {
+					languages: ['typescript'],
+					metadata: {},
+					cells: []
+				};
+			}
+
 			return {
 				languages: ['typescript'],
 				metadata: {},

extensions/vscode-notebook-tests/test/empty.vsctestnb

+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/