`.bind` calls in custom renderer docs pass container as 'this' value, not first param

[RoystonS]

The library README includes the following bit of sample code when suggesting how to write a custom renderer in order to change the 'testid' attribute:

const customRender = (container, options) => {
  const utils = render(container, options)

  return {
    ...utils,
    getByTestId: getByTestId.bind(container),
    getAllByTestId: getAllByTestId.bind(container),
    queryByTestId: queryByTestId.bind(container),
    queryAllByTestId: queryAllByTestId.bind(container),
  }
}

I might have got completely the wrong end of the stick, but should those .bind() calls not have en extra first null parameter? Otherwise they're passing container in as the this value to those functions rather than as the first parameter, as I think is intended?

Suggested solution:

Change them all to .bind(null, container)

Happy to submit a PR...

[alexkrolick]

Right... Let's just change to arrow functions instead of bind.

[RoystonS]

i.e.

getByTestId: (...rest) => getByTestId(container, ...rest),

and so on...?

I'll get a custom renderer together (as we have used data-uia for our test ids for years), check it works, and submit a PR...

[RoystonS]

... and in fact I think it also needs to be:

getByTestId: (...rest) => getByTestId(utils.container, ...rest),

because we need to work with the actual container that was used, not just the incoming value (which might not be defined). (This just bit me in the real renderer I'm writing.)

I'll keep going until I have a custom renderer that works and then feed back.