Add specs for creating variants

This already works, but we want to make sure it stays that way!

spec/reflexes/products_reflex_spec.rb

@@ -36,8 +36,10 @@ describe ProductsReflex, type: :reflex, feature: :admin_style_v3 do
 
   describe '#bulk_update' do
     let!(:variant_a1) {
-      create(:variant, product: product_a, display_name: "Medium box", sku: "APL-01", price: 5.25,
-                       on_hand: 5, on_demand: false)
+      product_a.variants.first.tap{ |v|
+        v.update! display_name: "Medium box", sku: "APL-01", price: 5.25, on_hand: 5,
+                  on_demand: false
+      }
     }
     let!(:product_c) { create(:simple_product, name: "Carrots", sku: "CAR-00") }
     let!(:product_b) { create(:simple_product, name: "Bananas", sku: "BAN-00") }
@@ -101,6 +103,63 @@ describe ProductsReflex, type: :reflex, feature: :admin_style_v3 do
       expect(flash).to include success: "Changes saved"
     end
 
+    it "creates new variants" do
+      # Form field names:
+      #   '[products][0][id]' (hidden field)
+      #   '[products][0][name]'
+      #   '[products][0][variants_attributes][0][id]' (hidden field)
+      #   '[products][0][variants_attributes][0][display_name]'
+      #   '[products][0][variants_attributes][1][display_name]' (id is omitted for new record)
+      #   '[products][0][variants_attributes][2][display_name]' (more than 1 new record is allowed)
+      params = {
+        "products" => {
+          "0" => {
+            "id" => product_a.id.to_s,
+            "name" => "Pommes",
+            "variants_attributes" => {
+              "0" => {
+                "id" => variant_a1.id.to_s,
+                "display_name" => "Large box",
+              },
+              "1" => {
+                "display_name" => "Small box",
+                "sku" => "POM-02",
+                "price" => "5.25",
+                "unit_value" => "0.5",
+              },
+              "2" => {
+                "sku" => "POM-03",
+                "price" => "15.25",
+                "unit_value" => "2",
+              },
+            },
+          },
+        },
+      }
+
+      expect{
+        run_reflex(:bulk_update, params:)
+        product_a.reload
+        variant_a1.reload
+      }.to change{ product_a.name }.to("Pommes")
+        .and change{ variant_a1.display_name }.to("Large box")
+        .and change{ product_a.variants.count }.by(2)
+
+      variant_a2 = product_a.variants[1]
+      expect(variant_a2.display_name).to eq "Small box"
+      expect(variant_a2.sku).to eq "POM-02"
+      expect(variant_a2.price).to eq 5.25
+      expect(variant_a2.unit_value).to eq 0.5
+
+      variant_a3 = product_a.variants[2]
+      expect(variant_a3.display_name).to be_nil
+      expect(variant_a3.sku).to eq "POM-03"
+      expect(variant_a3.price).to eq 15.25
+      expect(variant_a3.unit_value).to eq 2
+
+      expect(flash).to include success: "Changes saved"
+    end
+
     describe "sorting" do
       let(:params) {
         {

spec/services/sets/product_set_spec.rb

@@ -243,6 +243,46 @@ describe Sets::ProductSet do
           end
         end
       end
+
+      context "new variant" do
+        let(:variants_attributes) {
+          [
+            { id: product.variants.first.id.to_s }, # default variant unchanged
+            { sku: "new sku", price: "5.00", unit_value: "5" }, # omit ID for new variant
+          ]
+        }
+
+        it "creates new variant" do
+          expect {
+            product_set.save
+            expect(product_set.errors).to be_empty
+          }.to change { product.variants.count }.by(1)
+
+          expect(product.variants.last.sku).to eq "new sku"
+          expect(product.variants.last.price).to eq 5.00
+          expect(product.variants.last.unit_value).to eq 5
+        end
+
+        context "variant has error" do
+          let(:variants_attributes) {
+            [
+              { id: product.variants.first.id.to_s }, # default variant unchanged
+              { sku: "new sku", unit_value: "blah" }, # price missing, unit_value should be number
+            ]
+          }
+
+          include_examples "nothing saved"
+
+          it "logs variant errors" do
+            product_set.save
+            expect(product_set.errors.full_messages).to include(
+              "Variant price is not a number",
+              "Variant price can't be blank",
+              "Variant unit value is not a number"
+            )
+          end
+        end
+      end
     end
 
     context 'when there are multiple products' do