I am trying to get code coverage for the following controller. This is based on the calendar project found at https://github.com/sxg133/VFCalendar

/**
*   Controller for calendar component demo
*
*   @author Sahil Grover 
*/
public with sharing class CalendarController implements CalendarItemRetriever {

    public CalendarHandler Cal {get; private set;}
    public CalendarParameters CalParams {get; private set;}

    public CalendarController() {
        CalParams = new CalendarParameters();
        CalParams.SelectedView = CalendarParameters.CalendarView.MONTH;
        Cal = new CalendarHandler(this);
    }

    /**
    *   Get calendar items in a date range
    *
    *   @param  startDate   The start date (inclusive) to retrieve calendar items for
    *   @param  endDate     The end date (inclusive) to retrieve calendar items for
    *
    *   @return A list of CalendarItem objects
    */
    public List<CalendarItem> getCalendarItems(Date startDate, Date endDate) {
        List<CalendarItem> calendarItems = new List<CalendarItem>();
        // custom events
        List<Calendar_Event__c> customEvents = new List<Calendar_Event__c>([
            SELECT Id, Name, Description__c, Start_Date_Time__c,
                End_Date_Time__c, Is_All_Day__c, Link__c, Trainer__c
            FROM Calendar_Event__c
            WHERE Start_Date_Time__c >= :startDate
                AND End_Date_Time__c <= :endDate
            ]);
        for (Calendar_Event__c e : customEvents) {
            CalendarItem calItem = createCalendarItem(e);
            calendarItems.add(calItem);
        }

        return calendarItems;
    }

    private CalendarItem createCalendarItem(Calendar_Event__c e) {
        CalendarItem calItem = new CalendarItem(e.Id);
        calItem.Name = e.Name;
        calItem.Description = e.Description__c;
        calItem.StartDateTime = e.Start_Date_Time__c;
        calItem.EndDateTime = e.End_Date_Time__c;
        calItem.IsAllDay = e.Is_All_Day__c;
        calItem.Link = e.Link__c;
        calItem.Trainer = e.Trainer__c;
        calItem.CssClass = 'custom-event';
        return calItem;
    }
   
}

Test class
@isTest
private class CalendarControllerTest{

      private static testMethod void CalendarTest() {
             
        Test.startTest();
        CalendarController calendar = new CalendarController();
  
        Test.stopTest();

       } 
       
    }

It gets covered 50% simply by calling CalendarController calendar = new CalendarController(); in the Test.startTest() method.

I know this is probably a somewhat simple apex test question, but I cannot figure out how to get the rest of the code covered.

Any help is appreciated!