Remove now useless wrapper method

app/models/spree/inventory_unit.rb

@@ -35,16 +35,6 @@ module Spree
       end
     end
 
-    # This was refactored from a simpler query because the previous implementation
-    # lead to issues once users tried to modify the objects returned. That's due
-    # to ActiveRecord `joins(shipment: :stock_location)` only return readonly
-    # objects
-    #
-    # Returns an array of backordered inventory units as per a given stock item
-    def self.backordered_for_stock_item(stock_item)
-      backordered_per_variant(stock_item)
-    end
-
     def self.finalize_units!(inventory_units)
       inventory_units.map do |iu|
         iu.update_columns(

app/models/spree/stock_item.rb

@@ -16,7 +16,7 @@ module Spree
     delegate :name, to: :variant, prefix: true
 
     def backordered_inventory_units
-      Spree::InventoryUnit.backordered_for_stock_item(self)
+      Spree::InventoryUnit.backordered_per_variant(self)
     end
 
     def adjust_count_on_hand(value)

spec/models/spree/inventory_unit_spec.rb

@@ -6,47 +6,6 @@ RSpec.describe Spree::InventoryUnit do
   let!(:stock_location) { create(:stock_location_with_items) }
   let(:stock_item) { Spree::StockItem.order(:id).first }
 
-  context "#backordered_for_stock_item" do
-    let(:order) { create(:order) }
-
-    let(:shipment) do
-      shipment = Spree::Shipment.new
-      shipment.shipping_methods << create(:shipping_method)
-      shipment.order = order
-      # We don't care about this in this test
-      allow(shipment).to receive(:ensure_correct_adjustment)
-      shipment.tap(&:save!)
-    end
-
-    let!(:unit) do
-      unit = shipment.inventory_units.build
-      unit.state = 'backordered'
-      unit.variant_id = stock_item.variant.id
-      unit.tap(&:save!)
-    end
-
-    # Regression for Spree #3066
-    it "returns modifiable objects" do
-      units = Spree::InventoryUnit.backordered_for_stock_item(stock_item)
-      expect { units.first.save! }.not_to raise_error
-    end
-
-    it "finds inventory units from its stock location " \
-       "when the unit's variant matches the stock item's variant" do
-      expect(Spree::InventoryUnit.backordered_for_stock_item(stock_item)).to eq [unit]
-    end
-
-    it "does not find inventory units that don't match the stock item's variant" do
-      other_variant_unit = shipment.inventory_units.build
-      other_variant_unit.state = 'backordered'
-      other_variant_unit.variant = create(:variant)
-      other_variant_unit.save!
-
-      expect(Spree::InventoryUnit.backordered_for_stock_item(stock_item))
-        .not_to include(other_variant_unit)
-    end
-  end
-
   context "variants deleted" do
     let!(:unit) do
       Spree::InventoryUnit.create(variant: stock_item.variant)