public void When_associating_tasks_It_adds_is_once() { Task task = this.fixture.Create <Task>(); Plan plan = this.fixture.ConstructPlan(); plan.AssociateTask((TaskId)task.AggregateId, task.Summary().Name); plan.AssociateTask((TaskId)task.AggregateId, task.Summary().Name); plan.AssociateTask((TaskId)task.AggregateId, task.Summary().Name); Assert.AreEqual(1, plan.UncommittedChanges().OfType <TaskAssociatedToPlan>().Count(x => x.TaskId == task.AggregateId)); }