Test the following function : sanitizeEmail

Trying to test the following function to make sure it gets called and if its working properly Here is the function :

   sanitizeEmail = (email) => {
    let result = email;
    if(result.indexOf('@') !== -1 && result.substring(0,result.indexOf('@')).length > 3 ) {
     let end = result.indexOf('@');
     let temp = '';
     for(let i in result.substring(4,end)) {
    temp = temp + '*';
    }
   result = result.substring(0,3) + temp + result.substring(end, result.length);
}
return result
}

Using Jest and Enzyme for React Js

Here my test at the moment

beforeEach(() => wrapper = mount(<MemoryRouter keyLength={0}><ProfileMenuComponent {...baseProps} /></MemoryRouter>));

 it('Test componentDidMount method',() => {
  wrapper.setProps({
    user:{
     Email:""
    }
  })
 wrapper.find('ProfileMenuComponent').setState({
   permissionsLoaded:true,
   localPermissions:{[globals.UI_NOTIFICATION ]:true }
 });
wrapper.update();  

Not really sure how to work around with the 2 statements below:

expect(wrapper.find('ProfileMenuComponent').instance().componentDidMount()).toEqual();

expect(wrapper.find('ProfileMenuComponent').state('permissionsLoaded')).toBeTruthy();
 });