hi all,
i have written trigger but it gives only 44% code coverage so what can do forn increase it....?

My trigger is

trigger UpdateprdctonAcc on Subscription__c (after insert) 
{
    //Id recordTypeId = [Select Id From RecordType Where DeveloperName = 'User Group Membership'].Id;
    Id recordTypeId = Schema.SObjectType.Subscription__c.getRecordTypeInfosByName().get('User Group Membership').getRecordTypeId();
    List<Subscription__c> subscList = new List<Subscription__c>();

    for (Subscription__c s : Trigger.new){
        if(s.RecordTypeId == recordTypeId)
            subscList.add(s);
    }
    String str;
    
    Map<ID, Account> Acc = new Map<ID, Account>(); //Making it a map instead of list for easier lookup
    List<Id> listIds = new List<Id>();
    set<ID> cObjectID = new set<ID>();   //Making a set of Product ID's
    Map<ID, Account> updateMap = new Map<ID, Account>();
  
    for (Subscription__c s : subscList)
    {
        listIds.add(s.Company_Name__c);
      
        if(s.Membership_Type__c!= null)
        {
            cObjectID.add(s.Membership_Type__c);//takes the Lookup Record & Add that ID's in cObjectID set
        }
    }
    if(!cObjectID.isEmpty())
    {
        Map<ID,Product2> cObjectMap = new Map<ID,Product2>([select Id,Name from Product2 where Id IN: cObjectID]);
        Acc = new Map<Id, Account>([SELECT id,Product__c,(SELECT ID,Membership_Type__c FROM Subscriptions__r) FROM Account WHERE ID IN :listIds]);
        
        for(Subscription__c s : subscList)
        {   
            if(cObjectMap.get(s.Membership_Type__c).Name != Null)
            {
                // fill the country name on Opportunity with Country Name on Country_Object__c
                String pro= cObjectMap.get(s.Membership_Type__c).Name;
                Account myacc = acc.get(s.Company_Name__c);
                if(myacc != null){ //always check for nulls to avoid null pointer exceptions
                    myacc.Product__c=pro;
                    updateMap.put(myacc.Id,myacc);
                }
            }
        }
        update updateMap.values();
    }
}


and test class for this is....

@istest
public class TestPrdctonacc 
{
    static testMethod void verifyProductUpdation()
    {
     // Set up the Account record.
    Account a = new Account(Name='Test Account' ,SLA__c='Gold', SLAExpirationDate__c=Date.today(),SLASerialNumber__c='jhbfs');
    insert a;
    
    Product2 p=new Product2(Name='Product Name');
    insert p;
    
    test.startTest();
    // Verify that the initial state is as expected.
    a = [SELECT Name,Product__c FROM Account WHERE Id = :a.Id];
    System.assertEquals(null,a.Product__c);

    // Set up the Opportunity record.
    String company=a.Id;
    Subscription__c sub = new Subscription__c(Name='ABC',Company_Name__c=company,Membership_Type__c=p.Id);
    // Cause the Trigger to execute.
    insert sub;
  
     // Verify that the results are as expected.
    a = [SELECT Name, Product__c FROM Account WHERE Id = :a.Id];
    System.assertEquals(null, a.Product__c);
        test.stopTest();
    }   
}

please tell me answer in brief

Thanks,
Sam