react-native test example with jest

Header.js

import PropTypes from 'prop-types';
import React, { Component } from 'react';
import { View, Text } from 'react-native';

export default class Header extends Component {
  static propTypes = {
    user: PropTypes.object,
  }
  render() {
    return (
      <View>
        <Text key={ 'user' }>
          { this.props.user.name }
        </Text>
      </View>
    );
  }
}

Header.spec.js

import React from 'react';
import ReactShallowRenderer from 'react-test-renderer/shallow';

import { Header } from './';

describe('HeaderComponent', () => {
  /** @type {ReactShallowRenderer} */
  let renderer;
  let componentJSON;

  beforeEach(() => {
    renderer = new ReactShallowRenderer();
    renderer.render(
      <Header user={ { name: 'Bruno' } } />
    );
    componentJSON = renderer.getRenderOutput();
  });

  describe('Header on top', () => {
    it('should create component', () => {
      expect(componentJSON).toBeDefined();
    });

    describe('Component elements', () => {
      it('should display the name', () => {
        const usuario = componentJSON.props.children.find(child => child.key === 'user');
        expect(usuario.props.children).toBe('Bruno');
      });
    });
  });
});

jest.setup.js

global.XMLHttpRequest = require('xhr2');

package.json

  "jest": {
    "preset": "jest-expo",
    "setupFiles": [
      "./jest.setup.js"
    ]
  }