React: onChange is not a function - reactjs

Question

Am new to react and am trying to run unit test for a react app using jest,
The app using the Flux pattern and I have already wrote one component "WEATHER" and before move on to another one I wanted to write test for that component and take TDD approach.
My code running fine but the test fail with this error
TypeError: tree.props.onChange is not a function
The weather component code :
// #flow
import React from 'react';
import api from '../api';
import weatherStore from '../stores/weatherStore';
//read from weather store
let _getState = () => {
return {weather: weatherStore.returnWeather()};
};
export default class Weather extends React.Component {
constructor(proporties) {
super(proporties);
this._onChange = this._onChange.bind(this);
this.state = _getState();
}
componentWillUnmount() {
weatherStore.removeListener('change', this._onChange);
}
componentDidMount() {
api.getWeather();
weatherStore.on('change', this._onChange);
}
_onChange() {
this.setState(_getState());
}
render() {
let weatherState = this.state.weather.map(weather => {
return <div key={weather.id} className="pull-right row">
<div>
<span>{weather.main.temp} C</span><br />
</div>
</div>;
})
return <div>{weatherState}</div>;
}
}
Where the test code:
import React from 'react';
import Weather from '../js/components/Weather';
import renderer from 'react-test-renderer';
it('should render weather temp and city', ()=> {
const component = renderer.create(
<Weather />
);
let tree = component.toJSON();
expect(tree).toMatchSnapshot();
// manually trigger the callback
tree.props._onChange();
// re-rendering
tree = component.toJSON();
expect(tree).toMatchSnapshot();
});
Note since am using flow static type checker it always high light this line of code this._onChange = this._onChange.bind(this);
with error message saying : property '_onChange' property not found in the weather.

Answer 1

TypeError: tree.props.onChange is not a function
Have you tried updating your test with:
// manually trigger the callback
tree.props._onChange();
Note the dash.