Test class for trigger - triggers

Question

I just wrote this trigger and it seems to be working fine in dev, I need to move it into production, however, the test class I wrote passes the test but does not cover the trigger. Any help would be greatly appreciated. I am a bit green here. I know I should be inserting a contact (the account is a req field) then updating the contact field I just have no earthly clue how to do taht. Thank you
trigger PropOwned on Contact (after update) {
for (Contact c : Trigger.new) {
McLabs2__Ownership__c ownNew = new McLabs2__Ownership__c();
Contact oldContact = Trigger.oldMap.get(c.id);
if (c.One_Prop_Owned__c != oldContact.One_Prop_Owned__c && c.One_Prop_Owned__c != null) {
ownNew.McLabs2__Contact__c = c.id;
ownNew.McLabs2__Property__c = c.One_Prop_Owned__c;
insert ownNew;
}
}
}
This is the test class I wrote.
#isTest
public class TestOwnership {
static testMethod void createOwnership() {
McLabs2__Ownership__c ownNew = new McLabs2__Ownership__c();
ownNew.McLabs2__Contact__c = 'Michael Webb';
ownNew.McLabs2__Property__c = '131 West 33rd Street';
insert ownNew;
}
}

Answer 1

Your test class just creates a McLabs2__Ownership__c object and inserts this object in database. As a result of this trigger on McLabs2__Ownership__c(if exist) will be invoked, but you have to test a trigger on Contact object. Thus you need to insert an account and after that update it because your contact trigger works in after update mode.
So, you need something like that
#isTest
private class TestOwnership {
static testMethod void whenContactUpdatedNewOwnershipIsInserted() {
// create contact, you have to replace 'value1' with appropriate data type
Contact contact = new Contact(name = 'Test Contact', One_Prop_Owned__c = 'value1');
insert contact;
contact.One_Prop_Owned__c = 'value2'; // you have to replace value2 with appropriate data type
update contact;
// in this place you should has only one record of McLabs2__Ownership__c in database, because in test context real data isn't visible
List<McLabs2__Ownership__c> ownerships = [SELECT Id, McLabs2__Contact__c, McLabs2__Property__c FROM McLabs2__Ownership__c];
System.assertEquals(1, ownerships.size());
System.assertEquals(contact.Id, ownerships[0].McLabs2__Contact__c);
System.assertEquals(contact.One_Prop_Owned__c, ownerships[0].McLabs2__Property__c);
}
}
Read the following articles which might be pretty useful for you:
Apex Trigger best practice
SOQL in loop