public void AddCompartment() { var name = "London"; var existingCompartment = new ShoppingOrder(new ArticleGroup("Vegetables"), 30); var compartments = new Collection <ShoppingOrder> { existingCompartment }; var compartmentToAdd = new ShoppingOrder(new ArticleGroup("Vegetables"), 40); var testee = new Store(name, compartments); testee.AddCompartment(compartmentToAdd); testee.Compartments.Should().BeEquivalentTo(new [] { existingCompartment, compartmentToAdd }); }