function assertIsMobile(uaString, uaData) {
  util.setUserAgent(uaString);
  util.setUserAgentData(uaData || null);
  setUseClientHintsForTesting(!!uaData);
  assertTrue(device.isMobile());
  assertFalse(device.isTablet());
  assertFalse(device.isDesktop());
}
@param {?string} uaString
@param {?NavigatorUAData=} uaData