function assertInvalidFormat(format, args = undefined) {
  const exception = assertThrows(Const.unwrap(format), () => {
    TrustedResourceUrl.format(format, args || {});
  });
  assertContains('Invalid TrustedResourceUrl format', exception.message);
}
Asserts that format with no arguments throws.
@param {!Const} format
@param {!Object<string|number|!Const>=} args