Fix issue #8666 (#10739)

* fix issue #8666

* add issue #8666 test

components/menu/SubMenu.tsx

@@ -7,6 +7,8 @@ class SubMenu extends React.Component<any, any> {
   static contextTypes = {
     antdMenuTheme: PropTypes.string,
   };
+  // fix issue:https://github.com/ant-design/ant-design/issues/8666
+  static isSubMenu = 1;
   private subMenu: any;
   onKeyDown = (e: React.MouseEvent<HTMLElement>) => {
     this.subMenu.onKeyDown(e);

components/menu/__tests__/index.test.js

@@ -14,6 +14,23 @@ describe('Menu', () => {
     jest.useRealTimers();
   });
 
+  it('If has select nested submenu item ,the menu items on the grandfather level should be highlight', () => {
+    const wrapper = mount(
+      <Menu defaultSelectedKeys={['1-3-2']} mode="vertical">
+        <SubMenu key="1" title="submenu1">
+          <Menu.Item key="1-1">Option 1</Menu.Item>
+          <Menu.Item key="1-2">Option 2</Menu.Item>
+          <SubMenu key="1-3" title="submenu1-3">
+            <Menu.Item key="1-3-1">Option 3</Menu.Item>
+            <Menu.Item key="1-3-2">Option 4</Menu.Item>
+          </SubMenu>
+        </SubMenu>
+        <Menu.Item key="2">menu2</Menu.Item>
+      </Menu>
+    );
+    expect(wrapper.find('.ant-menu-submenu-selected').length).toBe(1);
+  });
+
   it('should accept defaultOpenKeys in mode horizontal', () => {
     const wrapper = mount(
       <Menu defaultOpenKeys={['1']} mode="horizontal">