function expectOk(linkText, linkUrl, opt_openInNewWindow, opt_noFollow) {
  mockOkHandler.handleEvent(new ArgumentMatcher(
      (arg) => arg.type == AbstractDialog.EventType.OK &&
          arg.linkText == linkText && arg.linkUrl == linkUrl &&
          arg.openInNewWindow == !!opt_openInNewWindow &&
          arg.noFollow == !!opt_noFollow,
      `{linkText: ${linkText}, linkUrl: ${linkUrl}` +
          ', openInNewWindow: ' + opt_openInNewWindow +
          ', noFollow: ' + opt_noFollow + '}'));
}
Sets up the mock event handler to expect an OK event with the given text
and url.
@suppress {missingProperties} suppression added to enable type checking