I'm trying to test a trigger that runs on a before delete on an account. When I delete the account in the test I thought that the child contacts would be delete as well but that does not seem to be the case. I don't understand what I'd doing wrong here.

String testuser = UserInfo.getUserID();
        //set up the account
         Account testacct = NewObjFactory.buildTestAcct(0, 'Test Account1', testuser);
        insert testacct;
        Account testacct2 = NewObjFactory.buildTestAcct(0, 'Test Account2', testuser);
        insert testacct2;
        String accid = testacct.id;
         // Create the Contacts
        Contact testcontact = NewObjFactory.buildTestContact(0, testacct.id, testuser, 'Cool', 'Joe');
        insert testcontact;
        String cid = testcontact.id;
        Contact testcontact2 = NewObjFactory.buildTestContact(0, testacct.id, testuser, 'Cool', 'John');
        insert testcontact2;
        String c2id = testcontact2.id;
        Contact testcontact3 = NewObjFactory.buildTestContact(0, testacct.id, testuser, 'Cool', 'Paul');
        insert testcontact3;
        
        
        //Create the portal records
        Portal_User_Information__c pu1 = new Portal_User_Information__c();
        pu1.user_Name__c = testcontact.id;
        insert pu1;
        
        Portal_User_Information__c pu2 = new Portal_User_Information__c();
        pu2.user_Name__c = testcontact2.id;
        insert pu2;
        
        Portal_User_Information__c pu3 = new Portal_User_Information__c();
        pu3.user_Name__c = testcontact3.id;
        insert pu3;
        String pu3id = pu3.id;

		
        //run tests
        Account ac = [Select ID from account where id = :accid];
        Contact c1 = [Select ID from contact where id = :cid];
        Test.startTest();
        	Database.deleteResult result = Database.delete(ac, false);  //delete account rec
			Database.deleteResult result2 = Database.delete(c1, false);
        Test.stopTest();
        
        // Check data 
        system.debug('start');      
        System.assert(result.isSuccess());
        System.assert(result2.isSuccess());
        system.debug('acct del2');
        Contact[] c1s = [Select ID from contact where id = :cid];
        System.assertEquals(c1s.size(),0);

Below is my test method. The last assert fails.