ReactWrapper::state() can only be called on class components

Writing unit testing in react using jest and enzyme. While checking with a component state , it throws an error "ReactWrapper::state() can only be called on class components ".
```jsx
import React from 'react';
import { mount } from 'enzyme';
import expect from 'expect';
import CustomerAdd from '../CustomerAdd'
import MUITheme from '../../../../Utilities/MUITheme';
import { ThemeProvider } from '@material-ui/styles';

describe('', () => {
const wrapper = mount(



);
test('something', () => {
expect(wrapper.find(CustomerAdd).state('addNewOnSubmit')).toEqual(true);
});
});
```
In the above code CustomerAdd Component is class component.I don't what wrong with my code. Can any one help me out of this problem. Thanks in advance.

Start by reproducing the reported test with mount, ThemeProvider, CustomerAdd, and wrapper.find(CustomerAdd).state('addNewOnSubmit'). Then inspect the Enzyme ReactWrapper state behavior and the CustomerAdd component; the report does not name a repository file, failing test path, or acceptance condition, so the intended fix is not yet defined.

Written by the indexing model from the issue text.