I was trying to get a good coverage for a trigger , but no luck so far

here is my trigger on Opportunity

Map<String, Integer> classificationTypePriorities = new Map<String, Integer>{
            'Sustainer' => 1,
            'Donor' => 2,
            'Fundraiser' => 3,
            'Buyer' => 4,
            'Activist' => 5,
            'Volunteer' => 6,
            'Prospect' => 7,
            'Lead' => 8
        };
        Map<String, Id> classificationTypes = new Map<String, Id>();
        for (cv__Engagement_Channel__c c : [SELECT Id, Name FROM cv__Engagement_Channel__c WHERE Name IN :classificationTypePriorities.keySet()]) {
            classificationTypes.put(c.Name, c.Id);
           
        }

for(Opportunity opp : trigger.new){

if(opp.RecordTypeId == rd.Id && opp.cv__Contact__r.cv__Primary_Engagement_Channel__r.id ==classificationTypes.get('Prospect')&& (opp.Child_ID__c == null || opp.Child_ID__c == ''))

conids.add(opp.cv__Contact__c);
}

 and the test clas is

static testMethod void testAssignmentType()
    {
      
     List<cv__Engagement_Channel__c> classificationTypesList = new List<cv__Engagement_Channel__c>{
            new cv__Engagement_Channel__c(Name = 'Sustainer'),
            new cv__Engagement_Channel__c(Name = 'Donor'),
            new cv__Engagement_Channel__c(Name = 'Fundraiser'),
            new cv__Engagement_Channel__c(Name = 'Buyer'),
            new cv__Engagement_Channel__c(Name = 'Activist'),
            new cv__Engagement_Channel__c(Name = 'Volunteer'),
             new cv__Engagement_Channel__c(Name = 'Prospect'),
            new cv__Engagement_Channel__c(Name = 'Lead')
                 };
        insert classificationTypesList;
       
          Map<String , Id> classificationTypes = new Map<String, Id>();
        for (cv__Engagement_Channel__c ct : classificationTypesList) {
            classificationTypes.put(ct.Name, ct.Id);
        }

List<RecordType> rt = [Select Id From RecordType Where Name = 'Household' and SobjectType = 'Account'];
        Account a = new Account();
        a.recordtypeId = rt[0].Id;
        a.Name = 'Test';
        insert a;
              
        Contact c = new Contact();
        c.lastName='testing';
        c.Client_Id__c = '42412';
        c.AccountId = a.Id;
      c.cv__Primary_Engagement_Channel__c = classificationTypes.get('Prospect');
        c.cv__Addressee__c = 'Mr.xyz';
           insert c;
            
          
RecordType rd = [SELECT Id FROM RecordType WHERE SObjectType = 'Opportunity' AND Name = 'Recurring Donation'];
       
        Opportunity opp = new Opportunity();
                    opp.RecordTypeId = rd.Id;
                    opp.cv__Recurring_Gift__c = rg.id;
                    opp.Name = 'Test Opp';
                    opp.AccountId = a.id;
                    opp.cv__Contact__c = c.id;
                     opp.CampaignId = cn.id;
                    opp.Amount = 30;
                    opp.CloseDate = Date.today();
                    opp.StageName = 'Received';
                    opp.cv__Payment_Type__c = 'Check';
        insert opp;
       System.debug('primary classification'+opp.cv__Contact__r.cv__Primary_Engagement_Channel__c) ;

Not sure whats going on but the debug logs shows opp.cv__Contact__r.cv__Primary_Engagement_Channel__c as null . Any help is appreciated