public class TestTriggers {
  static testMethod void myTest() {
   Date futureDate = date.newInstance(2050, 6, 6);
    Account account = new Account(name='testAccount', OfficeOwningAccount__c='VIC', Industry='Defence');
    insert account;
    account = [select name from Account where name=:account.name];
    Opportunity opp = new Opportunity(name='testOpp', accountID=account.ID, StageName='1.0 - Territory', CloseDate = futureDate);
    insert opp;
    opp = [select ID, name, StageName, Primary_Contact__c, PricingMethod__c from Opportunity where ID=:opp.ID];
    Contact contact = new Contact(lastname='testContact', accountID=account.ID);
    insert contact;
    contact = [select name from Contact where LastName=:contact.lastname];
    OpportunityContactRole oppContact = new OpportunityContactRole(IsPrimary = true, ContactID=contact.ID, OpportunityID=opp.ID);
    insert oppContact;
    oppContact = [select Id, isPrimary from OpportunityContactRole where OpportunityID=:oppContact.OpportunityID and ContactID=:oppContact.ContactID];
    Practice_Service_Offering__c practiceService = new Practice_Service_Offering__c(Opportunity__c = opp.ID, of_Sale__c = 100);
    insert practiceService;
    practiceService = [select Id from Practice_Service_Offering__c where Opportunity__c = :opp.ID];
    update opp;
    opp.name = 'testOppUpdate';
    opp.StageName = '7.0 - Win';
    opp.ENGAGEMENTSTARTDATE__C = futureDate;
    opp.ENGAGEMENTCLOSEDATE__C = futureDate;
    opp.HOURS_PER_DAY__C = 8;
    opp.PRICINGMETHOD__C = 'Fixed-Price';
    opp.PROPOSED_CONSULTANTS_AGREED_BILLING_RA__C = 'testBillRate';
    opp.AMOUNT = 20000;
//This info is all required fields for something at Stage 7
//When something goes to stage 7, IsClosed switches to true
    update opp;
    opp = [select ID, name, IsClosed, StageName, Primary_Contact__c, PricingMethod__c from Opportunity where ID=:opp.ID];
//Assertions go here:
    System.assert(account != null);
    System.assert(contact != null);
    System.assert(oppContact != null);
    System.assert(practiceService != null);
    System.assert(opp.PricingMethod__c == 'Fixed-Price');
    System.assert(opp.name == 'testOppUpdate');
    System.assert(opp.IsClosed);
    System.assert(opp.Primary_Contact__c != null);
     try {
       delete opp;
       delete account;
       delete oppContact;
       delete contact;
       delete practiceService;
       }
     catch (DmlException e) {
       e.getDmlMessage(0);
       System.assert(false);
     }
 System.assert(opp==null);
    }
}

trigger SetPrimaryContact on Opportunity (before update) {

    for (Opportunity o : Trigger.new) {
     //innitialise variables
     OpportunityContactRole contactRole;
     //Check that the opportunity is being closed out
      if (o.IsClosed && !Trigger.oldMap.get(o.id).IsClosed) {
     contactRole = [select ContactID from OpportunityContactRole where IsPrimary = true and OpportunityId = :o.id];
      }
      //if something is returned from the list:
      //get the primary contact associated with opp and assign the id to primary contact field
    if(contactRole != null){
    o.Primary_Contact__c = contactRole.ContactID;
    }
    //Profit
   }
}