如何使用 react-testing-library 测试 react-select

Question

App.js

import React, { Component } from "react";
import Select from "react-select";

const SELECT_OPTIONS = ["FOO", "BAR"].map(e => {
  return { value: e, label: e };
});

class App extends Component {
  state = {
    selected: SELECT_OPTIONS[0].value
  };

  handleSelectChange = e => {
    this.setState({ selected: e.value });
  };

  render() {
    const { selected } = this.state;
    const value = { value: selected, label: selected };
    return (
      <div className="App">
        <div data-testid="select">
          <Select
            multi={false}
            value={value}
            options={SELECT_OPTIONS}
            onChange={this.handleSelectChange}
          />
        </div>
        <p data-testid="select-output">{selected}</p>
      </div>
    );
  }
}

export default App;

App.test.js

import React from "react";
import {
  render,
  fireEvent,
  cleanup,
  waitForElement,
  getByText
} from "react-testing-library";
import App from "./App";

afterEach(cleanup);

const setup = () => {
  const utils = render(<App />);
  const selectOutput = utils.getByTestId("select-output");
  const selectInput = document.getElementById("react-select-2-input");
  return { selectOutput, selectInput };
};

test("it can change selected item", async () => {
  const { selectOutput, selectInput } = setup();
  getByText(selectOutput, "FOO");
  fireEvent.change(selectInput, { target: { value: "BAR" } });
  await waitForElement(() => getByText(selectOutput, "BAR"));
});

This minimal example works as expected in the browser but the test fails. I think the onChange handler in is not invoked. How can I trigger the onChange callback in the test? What is the preferred way to find the element to fireEvent at? Thank you

Answer 1

In my project, I'm using react-testing-library and jest-dom. I ran into same problem - after some investigation I found solution, based on thread: https://github.com/airbnb/enzyme/issues/400

Notice that the top-level function for render has to be async, as well as individual steps.

There is no need to use focus event in this case, and it will allow to select multiple values.

Also, there has to be async callback inside getSelectItem.

const DOWN_ARROW = { keyCode: 40 };

it('renders and values can be filled then submitted', async () => {
  const {
    asFragment,
    getByLabelText,
    getByText,
  } = render(<MyComponent />);

  ( ... )

  // the function
  const getSelectItem = (getByLabelText, getByText) => async (selectLabel, itemText) => {
    fireEvent.keyDown(getByLabelText(selectLabel), DOWN_ARROW);
    await waitForElement(() => getByText(itemText));
    fireEvent.click(getByText(itemText));
  }

  // usage
  const selectItem = getSelectItem(getByLabelText, getByText);

  await selectItem('Label', 'Option');

  ( ... )

}

Answer 2

This got to be the most asked question about RTL :D

The best strategy is to use jest.mock (or the equivalent in your testing framework) to mock the select and render an HTML select instead.

For more info on why this is the best approach, I wrote something that applies to this case too. The OP asked about a select in Material-UI but the idea is the same.

Original question and my answer:

Because you have no control over that UI. It's defined in a 3rd party module.

So, you have two options:

You can figure out what HTML the material library creates and then use container.querySelector to find its elements and interact with it. It takes a while but it should be possible. After you have done all of that you have to hope that at every new release they don't change the DOM structure too much or you might have to update all your tests.

The other option is to trust that Material-UI is going to make a component that works and that your users can use. Based on that trust you can simply replace that component in your tests for a simpler one.

Yes, option one tests what the user sees but option two is easier to maintain.

In my experience the second option is just fine but of course, your use-case might be different and you might have to test the actual component.

This is an example of how you could mock a select:

jest.mock("react-select", () => ({ options, value, onChange }) => {
  function handleChange(event) {
    const option = options.find(
      option => option.value === event.currentTarget.value
    );
    onChange(option);
  }
  return (
    <select data-testid="select" value={value} onChange={handleChange}>
      {options.map(({ label, value }) => (
        <option key={value} value={value}>
          {label}
        </option>
      ))}
    </select>
  );
});

You can read more here .

Answer 3

Finally, there is a library that helps us with that: https://testing-library.com/docs/ecosystem-react-select-event . Works perfectly for both single select or select-multiple:

From @testing-library/react docs:

import React from 'react'
import Select from 'react-select'
import { render } from '@testing-library/react'
import selectEvent from 'react-select-event'

const { getByTestId, getByLabelText } = render(
  <form data-testid="form">
    <label htmlFor="food">Food</label>
    <Select options={OPTIONS} name="food" inputId="food" isMulti />
  </form>
)
expect(getByTestId('form')).toHaveFormValues({ food: '' }) // empty select

// select two values...
await selectEvent.select(getByLabelText('Food'), ['Strawberry', 'Mango'])
expect(getByTestId('form')).toHaveFormValues({ food: ['strawberry', 'mango'] })

// ...and add a third one
await selectEvent.select(getByLabelText('Food'), 'Chocolate')
expect(getByTestId('form')).toHaveFormValues({
  food: ['strawberry', 'mango', 'chocolate'],
})

Thanks https://github.com/romgain/react-select-event for such an awesome package!

Answer 4

Similar to @momimomo's answer, I wrote a small helper to pick an option from react-select in TypeScript.

Helper file:

import { getByText, findByText, fireEvent } from '@testing-library/react';

const keyDownEvent = {
    key: 'ArrowDown',
};

export async function selectOption(container: HTMLElement, optionText: string) {
    const placeholder = getByText(container, 'Select...');
    fireEvent.keyDown(placeholder, keyDownEvent);
    await findByText(container, optionText);
    fireEvent.click(getByText(container, optionText));
}

Usage:

export const MyComponent: React.FunctionComponent = () => {
    return (
        <div data-testid="day-selector">
            <Select {...reactSelectOptions} />
        </div>
    );
};

it('can select an option', async () => {
    const { getByTestId } = render(<MyComponent />);
    // Open the react-select options then click on "Monday".
    await selectOption(getByTestId('day-selector'), 'Monday');
});

Answer 5

This solution worked for me.

fireEvent.change(getByTestId("select-test-id"), { target: { value: "1" } });

Hope it might help strugglers.

Answer 6

export async function selectOption(container: HTMLElement, optionText: string) {
  let listControl: any = '';
  await waitForElement(
    () => (listControl = container.querySelector('.Select-control')),
  );
  fireEvent.mouseDown(listControl);
  await wait();
  const option = getByText(container, optionText);
  fireEvent.mouseDown(option);
  await wait();
}

NOTE: container: container for select box ( eg: container = getByTestId('seclectTestId') )

Answer 7

An alternative solution which worked for my use case and requires no react-select mocking or separate library (thanks to @Steve Vaughan ) found on the react-testing-library spectrum chat.

The downside to this is we have to use container.querySelector which RTL advises against in favour of its more resillient selectors.

Answer 8

In case you are not using a label element, the way to go with react-select-event is:

const select = screen.container.querySelector(
  "input[name='select']"
);

selectEvent.select(select, "Value");

Answer 9

if for whatever reason there is a label with the same name use this

const [firstLabel, secondLabel] = getAllByLabelText('State');
    await act(async () => {
      fireEvent.focus(firstLabel);
      fireEvent.keyDown(firstLabel, {
        key: 'ArrowDown',
        keyCode: 40,
        code: 40,
      });

      await waitFor(() => {
        fireEvent.click(getByText('Alabama'));
      });

      fireEvent.focus(secondLabel);
      fireEvent.keyDown(secondLabel, {
        key: 'ArrowDown',
        keyCode: 40,
        code: 40,
      });

      await waitFor(() => {
        fireEvent.click(getByText('Alaska'));
      });
    });

or If you have a way to query your section—for example with a data-testid—you could use within:

within(getByTestId('id-for-section-A')).getByLabelText('Days')
within(getByTestId('id-for-section-B')).getByLabelText('Days')

Answer 10

Because I wanted to test a component that wrapped react-select , mocking it with a regular <select> element wouldn't have worked. So I ended up using the same approach that the package's own tests use, which is supplying a className in props and then using it with querySelector() to access the rendered element in the test:

const BASIC_PROPS: BasicProps = {
  className: 'react-select',
  classNamePrefix: 'react-select', 
  // ...
};

let { container } = render(
  <Select {...props} menuIsOpen escapeClearsValue isClearable />
);
fireEvent.keyDown(container.querySelector('.react-select')!, {
  keyCode: 27,
  key: 'Escape',
});
expect(
  container.querySelector('.react-select__single-value')!.textContent
).toEqual('0');

Answer 11

An easy way to test is by doing what the user should do

• Click on the select field.
• Click on one of the items in the dropdown list.

function CustomSelect() {

  const colourOptions = [
    { value: 'orange', label: 'Orange', color: '#FF8B00' },
    { value: 'yellow', label: 'Yellow', color: '#FFC400' }
  ]

  return <Select 
    aria-label="my custom select" 
    options={colourOptions}
    //... props  
  />
}

import { act, render, screen } from '@testing-library/react'; 
import userEvent from '@testing-library/user-event';
// another imports

test('show selected item...', async () => {
  const { getByText, getByLabelText } = render(<CustomSelect />);

  expect(getByText('Orange')).not.toBeInTheDocument();
  
  const myCustomSelect = getByLabelText(/my custom select/i);
  await act(async () => userEvent.click(myCustomSelect));

  const selectedItem = getByText('Orange');
  await act(async () => userEvent.click(selectedItem));

  expect(getByText('Orange')).toBeInTheDocument();
});