function assertSignInSuccessCallbackInvoked(
    user, opt_credential, opt_redirectUrl) {
  assertObjectEquals(user, signInCallbackUser);
  assertObjectEquals(opt_credential, signInCallbackCredential);
  assertEquals(opt_redirectUrl, signInCallbackRedirectUrl);
}
@param {?firebase.User} user The signed in user.
@param {?firebase.auth.AuthCredential=} opt_credential The auth credential.
@param {string=} opt_redirectUrl The redirect URL if available.