react-navigation/src/navigators/__tests__/StackNavigator-test.js

import React, { Component } from 'react';
import { View } from 'react-native';
import renderer from 'react-test-renderer';

import StackNavigator from '../StackNavigator';

class HomeScreen extends Component {
  static navigationOptions = ({ navigation }) => ({
    title: `Welcome ${navigation.state.params
      ? navigation.state.params.user
      : 'anonymous'}`,
    gesturesEnabled: true,
  });

  render() {
    return null;
  }
}

const routeConfig = {
  Home: {
    screen: HomeScreen,
  },
};

describe('StackNavigator', () => {
  it('renders successfully', () => {
    const MyStackNavigator = StackNavigator(routeConfig);
    const rendered = renderer.create(<MyStackNavigator />).toJSON();

    expect(rendered).toMatchSnapshot();
  });

  it('applies correct values when headerRight is present', () => {
    const MyStackNavigator = StackNavigator({
      Home: {
        screen: HomeScreen,
        navigationOptions: {
          headerRight: <View />,
        },
      },
    });
    const rendered = renderer.create(<MyStackNavigator />).toJSON();

    expect(rendered).toMatchSnapshot();
  });
});