redirect on browser success, but redirect on functional test is error

rubyonrails-talk
1

line_items.yml: one:   product_id: 1   cart_id: 1   quantity: 1

carts.yml: one: {}

product.rb: has_many :line_items

cart.rb: has_many :line_items, dependent: :destroy

line_item.rb: belongs_to :product belongs_to :cart

line_item_controller.rb: def destroy     @line_item = LineItem.find(params[:id])     @cart = @line_item.cart     @line_item.destroy

    respond_to do |format|       format.html { redirect_to @cart }       format.json { head :no_content }     end end

line_item_controller_test.rb:

    setup do         @line_item = line_items(:one)     end

    test "should destroy line_item" do       @cart = @line_item.cart       assert_difference('LineItem.count', -1) do       delete :destroy, id: @line_item     end

  assert_redirected_to @cart end

2

carts.yml does not create the cart with id=1 that LineItem.find(1) refers to.