fixes #13298

src/vs/base/common/comparers.ts

@@ -7,22 +7,26 @@
 import scorer = require('vs/base/common/scorer');
 import strings = require('vs/base/common/strings');
 
-const FileNameMatch = /^(.*)\.([^.]*)|([^.]+)$/;
+const FileNameMatch = /^([^.]*)(\.(.*))?$/;
 
 export function compareFileNames(one: string, other: string): number {
 	let oneMatch = FileNameMatch.exec(one.toLowerCase());
 	let otherMatch = FileNameMatch.exec(other.toLowerCase());
 
-	let oneName = oneMatch[1] || oneMatch[3] || '';
-	let oneExtension = oneMatch[2] || '';
+	let oneName = oneMatch[1] || '';
+	let oneExtension = oneMatch[3] || '';
 
-	let otherName = otherMatch[1] || otherMatch[3] || '';
-	let otherExtension = otherMatch[2] || '';
+	let otherName = otherMatch[1] || '';
+	let otherExtension = otherMatch[3] || '';
 
 	if (oneName !== otherName) {
 		return oneName < otherName ? -1 : 1;
 	}
 
+	if (oneExtension === otherExtension) {
+		return 0;
+	}
+
 	return oneExtension < otherExtension ? -1 : 1;
 }
 

src/vs/base/test/common/comparers.test.ts

+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+'use strict';
+
+import { compareFileNames } from 'vs/base/common/Comparers';
+import * as assert from 'assert';
+
+suite('Comparers', () => {
+
+	test('compareFileNames', () => {
+
+		assert(compareFileNames('', '') === 0, 'empty should be equal');
+		assert(compareFileNames('abc', 'abc') === 0, 'equal names should be equal');
+		assert(compareFileNames('.abc', '.abc') === 0, 'equal full names should be equal');
+		assert(compareFileNames('.env', '.env.example') < 0);
+		assert(compareFileNames('.env.example', '.gitattributes') < 0);
+	});
+});