userEvent.type not changing when is a empty string

I am experimenting this lib and may reached a possible bug. I have been writting a test for Input to check if erases it correctly and found something interesting.

import React from 'react';
import { render } from '@testing-library/react';
import userEvent from '@testing-library/user-event';

function Input(props) {
  return <input {...props} />;
}

it('should handle input erases', async () => {
    let value = '';
    const onChange = jest.fn(e => {
      value = e.target.value;
    });

    const { getByPlaceholderText, rerender } = render(
      <Input placeholder="Name" value={value} onChange={onChange} />
    );
    const input = getByPlaceholderText('Name');

    userEvent.type(input, 'test');

    // In order to see some "value" changes, we need to rerender the component
    rerender(<Input placeholder="Name" value={value} onChange={onChange} />);

    expect(input).toHaveAttribute('value', 'test');

    // When type empty string simulating an erase test will fail
    userEvent.type(input, '');
    // When using { allAtOnce: true } test will pass
    // userEvent.type(input, '', { allAtOnce: true });

    // In order to see some "value" changes, we need to rerender the component
    rerender(<Input placeholder="Name" value={value} onChange={onChange} />);

    expect(input).toHaveAttribute('value', '');
  });

When you use userEvent.type without { allAtOnce: true } on this case, the Input value will not get any updates. Looking at the type implementation I could identify what is possible wrong.

if (opts.allAtOnce) {
  if (element.readOnly) return;
  fireEvent.input(element, { target: { value: text } });
} else {
  let actuallyTyped = '';
  // If text is a empty string, actuallyTyped will never be used inside fireEvent.input
  for (let index = 0; index < text.length; index++) {
    ...
  }
}

If this is a real bug, I can help fix this! Maybe a naive solution could be adding a extra condition

if (opts.allAtOnce || text === '') 

What do you think guys?

[marquesm91]

Terrific ideia! Adding erase and shortcut will be possible to work better with userEvent abstractions!

I will start (maybe tonight) with erase to close this issue!

[weyert]

Sounds like a brilliant idea! I think this makes totally sense and feels to match the approach of this library (in my opinion). Typing and Erasing seems like a good combination.

I was thinking to write a helper userEvent.shortcut("{ctrl}{alt}m") to allow to type shortcuts easier. Not sure if it can be part of the type helper method.