`click` event has wrong `pointerType` of the string `"undefined"`

[stigi]

Reproduction example

Unit test case in issue

Prerequisites

import { createEvent } from '#src/event/createEvent'
import { render } from '#testHelpers'

test('it does not stringify click pointerType', () => {
    const { element } = render(`<input type="checkbox"/>`)
    const event = createEvent('click', element)
    expect(event).toHaveProperty('pointerType', undefined)
})

Expected behavior

Test passes

Actual behavior

 FAIL  tests/event/createEvent.ts
  ● it does not stringify click pointerType

    expect(received).toHaveProperty(path, value)

    Expected path: "pointerType"

    Expected value: undefined
    Received value: "undefined"

      5 |     const { element } = render(`<input type="checkbox"/>`)
      6 |     const event = createEvent('click', element)
    > 7 |     expect(event).toHaveProperty('pointerType', undefined)
        |                   ^
      8 | })
      9 |

      at Object.toHaveProperty (tests/event/createEvent.ts:7:19)

User-event version

14.6.1

Environment

Testing Library framework: @testing-library/react@13.4.0

JS framework: react@18.2.0

Test environment: jest@29.5.0

DOM implementation: jsdom@26.1.0

Additional context

Simulating a click does produce an event with an invalid pointerType of "undefined" (as string).

It is expected that pointerType can be undefined, but it should never be that string.

The cause for this is this line of code:

user-event/src/event/createEvent.ts

Line 271 in 63ac399

pointerType: String(pointerType),

I tried adding a simple PR that accounts for undefined here, but due to the nature of assignProps, the undefined value will be turned into null, which is also not correct:

user-event/src/event/createEvent.ts

Lines 101 to 105 in 63ac399

	function assignProps<T extends object>(obj: T, props: {[k in keyof T]?: T[k]}) {
	for (const [key, value] of Object.entries(props)) {
	Object.defineProperty(obj, key, {get: () => value ?? null})
	}
	}

Updating assignProps lead to too many snapshot changes, so I didn't pursue this further, but hope I've provided enough information that allows provide a fix.

Thanks 🙌

[james-camilleri]

This may be related to this change perhaps? #1219
I've had tests start failing since version 14.6.1, where a previously correct pointerType is now "undefined".