test: add test for isExternal

Author: sy-records

test/unit/core-util.test.js

@@ -60,10 +60,8 @@ describe('core/util', () => {
       expect(result).toBeTruthy();
     });
 
-    test('external url with two \\ ', () => {
-      const result = isExternal(
-        '/\\\\example.github.io/docsify/demo.md'
-      );
+    test('external url with two \\', () => {
+      const result = isExternal('/\\\\example.github.io/docsify/demo.md');
 
       expect(result).toBeTruthy();
     });