fix(isMobile): performance

Author: guoyunhe

tests/hooks.test.tsx

@@ -513,14 +513,12 @@ describe('hooks', () => {
         return <div>{isMobile ? 'mobile' : 'pc'}</div>;
       };
 
-      const { container } = render(<Demo />);
-      expect(container.textContent).toBe('pc');
-
       const navigatorSpy = jest
         .spyOn(navigator, 'userAgent', 'get')
         .mockImplementation(() => 'Android');
-      const { container: container2 } = render(<Demo />);
-      expect(container2.textContent).toBe('mobile');
+
+      const { container } = render(<Demo />);
+      expect(container.textContent).toBe('mobile');
 
       navigatorSpy.mockRestore();
     });