public async Task LogInTaskAsyncTask()
    {
        // テストデータ作成
        var user = await NCMBUser.LogInTaskAsync("tarou", "tarou");

        // 登録成功の確認
        Assert.AreEqual("dummySessionToken", NCMBUser._getCurrentSessionToken());
        Assert.AreEqual("tarou", user.UserName);
        Assert.AreSame(user, NCMBUser.CurrentUser);
        Assert.True(NCMBTestSettings.CallbackFlag);
    }