如何进行虚拟调用来检查令牌是否有效？

Question

我做了一个函数来知道一个人是否连接到API。创建新令牌后 我想知道令牌是否有效。我有点被困在这里。你如何进行虚拟调用并检查令牌的有效性？

private bool IsConnectedToFitbit()
{
    var access = StaminaFacade.GetBenefiaryAccess(this.Contact.EmployeeId,   ProviderCode.Fitbit);

    if (string.IsNullOrEmpty(access.AuthorizationKey1) || string.IsNullOrEmpty(access.AuthorizationKey2))
    return false;
    else
    {
        var tokens = new OAuthTokens
        {
            ConsumerKey = PortalSettings.FitbitAppId,
            ConsumerSecret = PortalSettings.FitbitAppSecret,
            AccessToken = access.AuthorizationKey1,
            AccessTokenSecret = access.AuthorizationKey2
        };

        //TODO: make a dummy call to fitbit to check if tokens are valid

        return true;