configure_event_settings.cls

public static void initializeEventSampleData(){

    UST_Event__c testEvent = new UST_Event__c (
        Name = 'Test Event',
        Event_Name__c = 'Test Event',
        Event_Type__c = 'Admissions Event',
        Event_Status__c = 'Active',
        Start_Date__c = System.Today(),
        End_Date__c = System.Today().addDays(7)
    );
    insert testEvent;

    UST_Event_Instance__c testEventInstance = new UST_Event_Instance__c (
        Event__c = testEvent.Id,
        Active_Status__c = 'Active',
        Start_Date_Time__c = System.Today(),
        End_Date_Time__c = System.Today().addDays(7)
    );
    insert testEventInstance;

}

public static void setSiteURL(){

    String siteName = 'UST_Events';

    Site site = [
        SELECT GuestUserId
        FROM Site
        WHERE Name = :siteName
    ];

    String path = '/sites/servlet.SiteDebugMode';
    PageReference pr = new PageReference(path);
    pr.getParameters().put('guid', site.GuestUserId);
    pr.getParameters().put('sitedebugmode', 'x');
    String url = pr.getContent().toString().substringAfter('URL=').substringBefore(path);

    UST_Event_Settings__c eventSettings = UST_Event_Settings__c.getOrgDefaults();    
    eventSettings.Community_Base_URL__c = url;
    upsert eventSettings;
    
}