ClassNameConfigurator will be removed, so it doesn't make sense to update its tests

The prop getters here should likely be memoized, so they can be passed to a memo'd component via the render prop where necessary. I also think it's cleaner to inline the event handlers inside the props themselves?

Done. As for inlining - I'm not entirely convinced. I don't like too many levels of indentation. I moved the event handlers closer to these functions so it's easier to see both at the same time

I'm mostly fine with either, but I do think inlining is simpler and the better option:

• You don't need to specify types for the parameters, and there's less indirection
• It's easier to read compared to the double function
• It's colocated with the other props
• The indentation is the same (8 spaces):

Separate

  const createHandleButtonClick = React.useCallback(
    (otherProps: React.ButtonHTMLAttributes<HTMLButtonElement>) =>
      (event: React.MouseEvent<HTMLButtonElement>) => {
        inputRef.current?.click();
12345678^
      },
    [readOnly],
  );

  const getButtonProps: UseSwitchReturnValue['getButtonProps'] = React.useCallback(
    (otherProps = {}) => ({
      onClick: createHandleButtonClick(otherProps),
    }),
    [checked, disabled, readOnly, createHandleButtonClick],
  );

Inline

  const getButtonProps: UseSwitchReturnValue['getButtonProps'] = React.useCallback(
    (otherProps = {}) => ({
      onClick(event) {
        inputRef.current?.click();
12345678^
      },
    }),
    [checked, disabled, readOnly],
  );

Overall, I'm not that concerned and think either is fine, but I feel inlining is easier to read and write.

The API docs show import { SwitchThumb } from '@mui/base/SwitchThumb' being possible. Should this be the case, or just have the generator updated to show Switch.Thumb usage?

It's an issue with the API docs generator I haven't fixed yet, but we can do this in a separate PR.