#19733 Default configurations

- Define a new extension point `configurationDefaults` for contributing default language specific editor settings

extensions/vscode-api-tests/src/configuration.test.ts

@@ -0,0 +1,20 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as assert from 'assert';
+import * as vscode from 'vscode';
+
+suite('Configuration tests', () => {
+
+	test('Default configurations', function () {
+		const defaultLanguageSettings = vscode.workspace.getConfiguration().get('[abcLang]');
+
+		assert.deepEqual(defaultLanguageSettings, {
+			'editor.lineNumbers': 'off',
+			'editor.tabSize': 2
+		});
+	});
+
+});