Spec for updating products with variants

Trying to cover it more comprehensively, and revealing we have a lot of behaviour to update.
Products and their variants should always get saved (or not saved) together. This is considered the most intuitive behaviour.

There's still duplication with the "variant has error" context, but I try to avoid nesting shared_examples, it starts to get ugly. Happy to discuss though.

spec/services/sets/product_set_spec.rb

@@ -129,32 +129,102 @@ describe Sets::ProductSet do
       end
     end
 
-    describe "updating variants" do
-      let!(:product) { create(:simple_product) }
-      let(:collection_hash) { { 0 => { id: product.id } } }
+    describe "updating a product's variants" do
+      let(:product) { create(:simple_product) }
+      let(:variant) { product.variants.first }
+      let(:product_attributes) { {} }
+      let(:variant_attributes) { { sku: "var_sku" } }
+      let(:variants_attributes) { [{ **variant_attributes, id: product.variants.first.id.to_s }] }
+      let(:collection_hash) {
+        {
+          0 => { id: product.id, **product_attributes, variants_attributes: }
+        }
+      }
 
-      context 'when :variants_attributes are passed' do
-        let(:variants_attributes) { [{ sku: '123', id: product.variants.first.id.to_s }] }
+      it "updates the variant" do
+        expect {
+          product_set.save
+          variant.reload
+        }.to change { variant.sku }.to("var_sku")
+      end
 
-        before { collection_hash[0][:variants_attributes] = variants_attributes }
-
-        it 'updates the attributes of the variant' do
+      shared_examples "nothing saved" do
+        it "doesn't update product" do
           expect {
-            expect(product_set.save).to eq true
-          }.to change { product.variants.first.sku }.to("123")
-
-          expect(product_set.invalid.count).to eq 0
+            product_set.save
+            product.reload
+          }.to_not change { product.sku }
         end
 
-        context 'and when product attributes are also passed' do
-          it 'updates product and variant attributes' do
-            collection_hash[0][:sku] = "test_sku"
+        it "doesn't update variant" do
+          expect {
+            product_set.save
+            variant.reload
+          }.to_not change { variant.sku }
+        end
 
-            expect {
-              product_set.save
-              product.reload
-            }.to change { product.sku }.to("test_sku")
-              .and change { product.variants.first.sku }.to("123")
+        it 'assigns the in-memory attributes of the variant' do
+          pending
+          expect {
+            product_set.save
+          }.to change { variant.sku }.to("123")
+        end
+      end
+
+      xcontext "variant has error" do
+        let(:variant_attributes) { { sku: "var_sku", display_name: "A" * 256 } } # maximum length
+
+        include_examples "nothing saved"
+      end
+
+      context "when products attributes are also updated" do
+        let(:product_attributes) {
+          { sku: "prod_sku" }
+        }
+
+        it "updates product and variant" do
+          expect {
+            product_set.save
+            product.reload
+          }.to change { product.sku }.to("prod_sku")
+            .and change { product.variants.first.sku }.to("var_sku")
+        end
+
+        xcontext "variant has error" do
+          let(:variant_attributes) { { sku: "var_sku", display_name: "A" * 256 } } # maximum length
+
+          include_examples "nothing saved"
+        end
+
+        context "product has error" do
+          before { collection_hash[0][:name] = "" } # product.name can't be blank
+
+          include_examples "nothing saved"
+        end
+      end
+
+      context "when multiple variants are updated" do
+        let(:variant2) { create(:variant, product:) }
+        let(:variants_attributes) {
+          [
+            { **variant_attributes, id: product.variants.first.id.to_s },
+            { sku: "var_sku2", id: variant2.id.to_s },
+          ]
+        }
+
+        it "updates each variant" do
+          expect {
+            product_set.save
+            variant2.reload
+          }.to change { product.variants.first.sku }.to("var_sku")
+            .and change { variant2.sku }.to("var_sku2")
+        end
+
+        xcontext "variant has error" do
+          let(:variant_attributes) { { sku: "var_sku", display_name: "A" * 256 } } # maximum length
+
+          include_examples "nothing saved" do
+            after { expect(variant2.reload.sku).to_not eq "var_sku2" }
           end
         end
       end