Apex Test for Invocable Method used in Visual Flow

global class TimeZoneConverter
{
    @InvocableMethod(label='Convert Timezone DateTime' description='Converts a date time timezone string to a DateTime value')
    public static List<Datetime> UTCdateValue(List<TimezoneConvertRequest> ConvertMe)
    {
        Timezone tz = Timezone.getTimeZone(ConvertMe[0].tzRequest); //now I have an official Timezone datatype variable tz
        Datetime dt = Datetime.parse(ConvertMe[0].dtRequest.format()); //now I have a UTC Datetime string
        Integer offsetMS = tz.getOffset(dt); //now I have the Milliseconds difference between the timezone selected and the UTC datetime string
        Integer offsetHrs = (((offsetMS / 1000)/60)/60)*-1; //now I have the offset in hours
        Datetime adjdt = dt.addHours(offsetHrs); //should be the adjusted value.
        List<Datetime> returnMe = new List<Datetime>();
        returnMe.add(adjdt);
        return returnMe;
    }
    global class TimezoneConvertRequest {
        @InvocableVariable(required=true)
        public String tzRequest;
        @InvocableVariable(required=true)
        public Datetime dtRequest;
    }
}

@isTest
	class TimeZoneConverterTest {
        @isTest static void testTimezoneConvertRequest() {
            Test.startTest();
            DateTime BroadcastItemDateTimeTest = Datetime.parse('2016-01-01 13:00:00');
            string Timezone_Selected = 'US/Eastern';
            List<TimeZoneConverter.TimezoneConvertRequest> testingThis = new List<TimeZoneConverter.TimezoneConvertRequest>();
            TimeZoneConverter.TimezoneConvertRequest ConvertMeTest = new TimeZoneConverter.TimezoneConvertRequest();
            ConvertMeTest.tzRequest = Timezone_Selected;
            ConvertMeTest.dtRequest = BroadcastItemDateTimeTest;
            testingThis.add(ConvertMeTest);
            TimeZoneConverter ConvertTest = new TimeZoneConverter();
            ConvertTest.UTCdateValue(TestingThis);
            DateTime testResponse = ConvertTest[0];
			Test.stopTest();
    System.assertEquals(Datetime.parse('2016-01-01 13:00:00'), testResponse);
    }
  }

ConvertTest.UTCdateValue(TestingThis);