public void can_change_primary_location()
{
var subject = new Provider() { Id = 1 };
var locationA = new OrgUnit() { Id = 1 };
var providerLocationA = subject.AddOrgUnit(locationA);
var locationB = new OrgUnit() { Id = 2 };
var providerLocationB = subject.AddOrgUnit(locationB);
subject.SetPrimaryOrgUnit(providerLocationB);
Assert.IsFalse(providerLocationA.IsPrimary.Value);
Assert.IsTrue(providerLocationB.IsPrimary.Value);
}