Spec total_units report column

Current reports don't deal with invalid legacy data.

spec/lib/reports/orders_and_fulfillment/orders_cycle_supplier_totals_report_spec.rb

@@ -29,6 +29,81 @@ describe Reporting::Reports::OrdersAndFulfillment::OrderCycleSupplierTotals do
     expect(report_table.length).to eq(1)
   end
 
+  describe "total_units column" do
+    let(:item) { order.line_items.first }
+    let(:variant) { item.variant }
+
+    it "contains a sum of total items" do
+      variant.product.update!(variant_unit: "items", variant_unit_name: "bottle")
+      variant.update!(unit_value: 6) # six-pack
+      item.update!(final_weight_volume: nil) # reset unit information
+      item.update!(quantity: 3)
+
+      expect(table_headers[4]).to eq "Total Units"
+      expect(report_table[0][4]).to eq 18 # = 3 * 6, three six-packs
+    end
+
+    it "contains a sum of total weight" do
+      variant.product.update!(variant_unit: "weight")
+      variant.update!(unit_value: 200) # grams
+      item.update!(final_weight_volume: nil) # reset unit information
+      item.update!(quantity: 3)
+
+      expect(table_headers[4]).to eq "Total Units"
+      expect(report_table[0][4]).to eq 0.6 # kg (= 3 * 0.2kg)
+    end
+
+    it "is blank when line items miss a unit" do
+      # This is not possible with the current code but was possible years ago.
+      # So I'm using `update_columns` to save invalid data.
+      # We still have lots of that data in our databases though.
+      variant.product.update(variant_unit: "items", variant_unit_name: "container")
+      variant.update_columns(unit_value: nil, unit_description: "vacuum")
+      item.update!(final_weight_volume: nil) # reset unit information
+
+      expect(table_headers[4]).to eq "Total Units"
+      expect(report_table[0][4]).to eq " "
+    end
+
+    it "is summarised" do
+      expect(report).to receive(:display_summary_row?).and_return(true)
+
+      variant.product.update!(variant_unit: "weight")
+      variant.update!(unit_value: 200) # grams
+      item.update!(final_weight_volume: nil) # reset unit information
+      item.update!(quantity: 3)
+
+      # And a second item to add up with:
+      item2 = create(:line_item, order: order)
+
+      expect(table_headers[4]).to eq "Total Units"
+      expect(report_table[0][4]).to eq 0.6 # kg (= 3 * 0.2kg)
+      expect(report_table[1][4]).to eq 0.001 # 1 gram default value
+      expect(report_table[2][4]).to eq 0.601 # summary
+    end
+
+    pending "is blank in summary when one line item misses a unit and another not" do
+      expect(report).to receive(:display_summary_row?).and_return(true)
+
+      # This is not possible with the current code but was possible years ago.
+      # So I'm using `update_columns` to save invalid data.
+      # We still have lots of that data in our databases though.
+      variant.product.update(variant_unit: "items", variant_unit_name: "container")
+      variant.update_columns(unit_value: nil, unit_description: "vacuum")
+      item.update!(final_weight_volume: nil) # reset unit information
+
+      # This second line item will have a default a bigint value.
+      order.line_items << create(:line_item)
+
+      # Generating the report used to raise:
+      # > TypeError: no implicit conversion of BigDecimal into String
+      expect(table_headers[4]).to eq "Total Units"
+      expect(report_table[0][4]).to eq " "
+      expect(report_table[1][4]).to eq 0.001 # 1 gram default value
+      expect(report_table[2][4]).to eq " " # summary
+    end
+  end
+
   context "with a VAT/GST-free supplier" do
     before(:each) do
       supplier.update(charges_sales_tax: false)