Add custom OFN product id to DFC SuppliedProduct

The Spree::Variant in OFN corresponds to a DFC SuppliedProduct. But
several Spree::Variant can be grouped under one Spree::Product which
wasn't exposed on the DFC API.

I'm adding a custom property here which can be used internally and
shouldn't break any other DFC tools.

A gotcha of this first test implementation:

The `ofn:` prefix has not been defined in the context. Software needs
to know that this is an Open Food Network attribute or ignore it.
We could define our own context and ontology and publish it on our
website but I don't see any benefit of that at this point.

engines/dfc_provider/app/services/supplied_product_builder.rb

@@ -13,7 +13,11 @@ class SuppliedProductBuilder < DfcBuilder
       description: variant.description,
       productType: product_type,
       quantity: QuantitativeValueBuilder.quantity(variant),
-    )
+    ).tap do |supplied_product|
+      supplied_product.registerSemanticProperty("ofn:spree_product_id") do
+        variant.product.id
+      end
+    end
   end
 
   def self.import(supplied_product)

engines/dfc_provider/spec/requests/catalog_items_spec.rb

@@ -15,7 +15,7 @@ describe "CatalogItems", type: :request, swagger_doc: "dfc.yaml",
   let(:product) {
     create(
       :base_product,
-      supplier: enterprise, name: "Apple", description: "Red",
+      id: 90_000, supplier: enterprise, name: "Apple", description: "Red",
       variants: [variant],
     )
   }

engines/dfc_provider/spec/requests/enterprises_spec.rb

@@ -22,7 +22,7 @@ describe "Enterprises", type: :request, swagger_doc: "dfc.yaml", rswag_autodoc:
   let!(:product) {
     create(
       :base_product,
-      supplier: enterprise, name: "Apple", description: "Round",
+      id: 90_000, supplier: enterprise, name: "Apple", description: "Round",
       variants: [variant],
     )
   }

engines/dfc_provider/spec/requests/supplied_products_spec.rb

@@ -9,6 +9,7 @@ describe "SuppliedProducts", type: :request, swagger_doc: "dfc.yaml",
   let!(:product) {
     create(
       :base_product,
+      id: 90_000,
       supplier: enterprise, name: "Pesto", description: "Basil Pesto",
       variants: [variant],
     )
@@ -78,7 +79,7 @@ describe "SuppliedProducts", type: :request, swagger_doc: "dfc.yaml",
           example.metadata[:operation][:parameters].first[:schema][:example]
         end
 
-        it "creates a variant" do |example|
+        it "creates a product and variant" do |example|
           expect { submit_request(example.metadata) }
             .to change { enterprise.supplied_products.count }.by(1)
 
@@ -87,16 +88,23 @@ describe "SuppliedProducts", type: :request, swagger_doc: "dfc.yaml",
             %r|^http://test\.host/api/dfc/enterprises/10000/supplied_products/[0-9]+$|
           )
 
+          spree_product_id = json_response["ofn:spree_product_id"].to_i
+
           variant_id = dfc_id.split("/").last.to_i
           variant = Spree::Variant.find(variant_id)
           expect(variant.name).to eq "Apple"
           expect(variant.unit_value).to eq 3
+          expect(variant.product_id).to eq spree_product_id
 
           # Insert static value to keep documentation deterministic:
           response.body.gsub!(
             "supplied_products/#{variant_id}",
             "supplied_products/10001"
           )
+            .gsub!(
+              "\"ofn:spree_product_id\":#{spree_product_id}",
+              '"ofn:spree_product_id":90000'
+            )
         end
       end
     end
@@ -116,6 +124,7 @@ describe "SuppliedProducts", type: :request, swagger_doc: "dfc.yaml",
 
         run_test! do
           expect(response.body).to include variant.name
+          expect(json_response["ofn:spree_product_id"]).to eq 90_000
         end
       end
 

swagger/dfc.yaml

@@ -118,6 +118,7 @@ paths:
                       dfc-b:lifetime: ''
                       dfc-b:usageOrStorageCondition: ''
                       dfc-b:totalTheoreticalStock: 0.0
+                      ofn:spree_product_id: 90000
                     - "@id": http://test.host/api/dfc/enterprises/10000/offers/10001
                       "@type": dfc-b:Offer
                       dfc-b:price: 19.99
@@ -341,6 +342,7 @@ paths:
                       dfc-b:lifetime: ''
                       dfc-b:usageOrStorageCondition: ''
                       dfc-b:totalTheoreticalStock: 0.0
+                      ofn:spree_product_id: 90000
                     - "@id": http://test.host/api/dfc/enterprises/10000/catalog_items/10001
                       "@type": dfc-b:CatalogItem
                       dfc-b:references: http://test.host/api/dfc/enterprises/10000/supplied_products/10001
@@ -409,6 +411,7 @@ paths:
                     dfc-b:lifetime: ''
                     dfc-b:usageOrStorageCondition: ''
                     dfc-b:totalTheoreticalStock: 0.0
+                    ofn:spree_product_id: 90000
       requestBody:
         content:
           application/json:
@@ -471,6 +474,7 @@ paths:
                     dfc-b:lifetime: ''
                     dfc-b:usageOrStorageCondition: ''
                     dfc-b:totalTheoreticalStock: 0.0
+                    ofn:spree_product_id: 90000
         '404':
           description: not found
     put: