Question

我在理解如何测试模态组件方面有些困难。我正在将react-native-modals软件包和@testing-library/react-native与Jest一起使用。我的组件是一个模态，当将GraphQL错误传递给它时会弹出。

./ ErrorMessage.js

import React from 'react';
import PropTypes from 'prop-types';
import { Dimensions, Text } from 'react-native';
import Modal, { ModalContent, ScaleAnimation } from 'react-native-modals';
import { theme } from '../styles/theme.styles';

const ModalError = ({ error, onClose }) => {
  if (!error || !error.message) {
    return (
      <Modal visible={false}>
        <Text />
      </Modal>
    );
  }

  return (
    <Modal
      visible
      modalAnimation={
        new ScaleAnimation({
          initialValue: 0,
          useNativeDriver: true,
        })
      }
      onTouchOutside={onClose}
      swipeDirection={['up', 'down', 'left', 'right']}
      swipeThreshold={200}
      onSwipeOut={onClose}
      modalStyle={modalStyle}
      overlayOpacity={0.7}
    >
      <ModalContent>
        <Text testID="graphql-error">{error.message}</Text>
      </ModalContent>
    </Modal>
  );
};

ModalError.defaultProps = {
  error: {},
};

ModalError.propTypes = {
  error: PropTypes.object,
  onClose: PropTypes.func.isRequired,
};

export default ModalError;

const window = Dimensions.get('window');

const modalStyle = {
  backgroundColor: theme.lightRed,
  borderLeftWidth: 5,
  borderLeftColor: theme.red,
  width: window.width / 1.12,
};

到目前为止，我的测试非常简单。我只想确保它正在渲染模态。我不确定在这里需要模仿什么或如何去做。

./__ tests __ / ErrorMessage.test.js

import React from 'react';
import { MockedProvider } from '@apollo/react-testing';
import { GraphQLError } from 'graphql';
import { render } from '@testing-library/react-native';
import Error from '../ErrorMessage';

jest.mock('react-native-modals', () => 'react-native-modals');

const error = new GraphQLError('This is a test error message.');
const handleOnCloseError = jest.fn();

describe('<ErrorMessage>', () => {
  it('should render an ErrorMessage modal component', () => {
    const { container } = render(
      <MockedProvider>
        <Error error={error} onClose={handleOnCloseError} />
      </MockedProvider>
    );
    expect(container).toMatchSnapshot();
  });
});

我得到的错误是...

TypeError: _reactNativeModals.ScaleAnimation is not a constructor

      18 |       visible
      19 |       modalAnimation={
    > 20 |         new ScaleAnimation({
         |         ^
      21 |           initialValue: 0,
      22 |           useNativeDriver: true,
      23 |         })

快照仅在打印...

./__ tests __ / __ snapshots __ / ErrorMessage.test.js.snap

// Jest Snapshot v1, 

exports[`<ErrorMessage> should render an ErrorMessage modal component 1`] = `
<View
  collapsable={true}
  pointerEvents="box-none"
  style={
    Object {
      "flex": 1,
    }
  }
/>
`;

如何克服此错误并制作适当的快照？

Answer 1

当您执行jest.mock('react-native-modals', () => 'react-native-modals');时，您要用字符串'react-native-modals'替换整个库，因此在组件中使用它时会失败。您需要从模拟函数（jest.mock的第二个参数）返回完整的模拟实现。只需执行以下操作即可自动嘲笑您：jest.mock('react-native-modals');

这是jest.mock（）的停靠点，其中包含各种使用方式的示例：https://jestjs.io/docs/en/jest-object#jestmockmodulename-factory-options。

Answer 2

你可以使用这个 -> https://github.com/testing-library/jest-native

In react native component,
...
<Modal
        testID="test-modal"
        deviceWidth={deviceWidth}
        deviceHeight={deviceHeight}
        isVisible={isModalVisible}.  // isModalVisible = useState(true or false)
        onBackdropPress={toggleModal}
        backdropOpacity={0.5}
 >
...

In test component,
...
const test = getByTestId("test-modal");
expect(test).toHaveProp("visible", true);   // test success ! 
...

如何使用Jest和本机测试库正确测试React Native Modals

2 个答案: