upload() doesn't convert file to an array with input multiple

[zaicevas]

Could someone explain to me the logic behind this line of code: https://github.com/testing-library/user-event/blob/master/src/upload.js#L17 ?

Consider this code snippet:

  function handleChooseImage(event: ChangeEvent<HTMLInputElement>) {
    const selectedFiles = event.target.files

    if (!selectedFiles?.length) return
   
    ...
  }

      <input
        data-testid="add-photos-input"
        ref={inputRef}
        type="file"
        onChange={handleChooseImage}
        accept="image/*"
        multiple
        hidden
      />

My goal is to write following lines of test code

      const imageFile = new File([], 'imgname', { type: 'image/png' })
      const imageInput = screen.getByTestId('add-photos-input')

      userEvent.upload(imageInput, imageFile)

This test code result in event handler being called with an object, where length is undefined and item() returns undefined:

selectedFiles: { length: undefined, item: [Function: item] }

Is that expected behaviour?

[ph-fritsche]

The function expects you to provide File for single file inputs and File[] for multiple file inputs.

userEvent.upload(multipleFileInput, [imageFile])

I think this could be improved by just converting it.

[ph-fritsche]

resolved in 12.6.2