Assign random product category on import if missing

Failing in this case may be desired in some circumstances but most of
the time we want compatibility and easy interoperability even when not
all data matches.

engines/dfc_provider/app/services/supplied_product_builder.rb

@@ -90,10 +90,11 @@ class SuppliedProductBuilder < DfcBuilder
   end
 
   def self.taxon(supplied_product)
-    return unless supplied_product.productType
+    dfc_id = supplied_product.productType&.semanticId
 
-    dfc_id = supplied_product.productType.semanticId
-    Spree::Taxon.find_by(dfc_id: )
+    # Every product needs a primary taxon to be valid. So if we don't have
+    # one or can't find it we just take a random one.
+    Spree::Taxon.find_by(dfc_id:) || Spree::Taxon.first
   end
 
   private_class_method :product_type, :taxon

engines/dfc_provider/spec/services/supplied_product_builder_spec.rb

@@ -64,14 +64,6 @@ describe SuppliedProductBuilder do
 
         expect(product.productType).to eq soft_drink
       end
-
-      context "when no taxon set" do
-        let(:taxon) { nil }
-
-        it "returns nil" do
-          expect(product.productType).to be_nil
-        end
-      end
     end
 
     it "assigns an image_url type" do
@@ -131,16 +123,6 @@ describe SuppliedProductBuilder do
 
         expect(product.primary_taxon).to eq(taxon)
       end
-
-      describe "when no matching taxon" do
-        let(:product_type) { DfcLoader.connector.PRODUCT_TYPES.DRINK }
-
-        it "set the taxon to nil" do
-          product = builder.import_product(supplied_product)
-
-          expect(product.primary_taxon).to be_nil
-        end
-      end
     end
   end
 
@@ -161,7 +143,10 @@ describe SuppliedProductBuilder do
     let(:product_type) { DfcLoader.connector.PRODUCT_TYPES.VEGETABLE.NON_LOCAL_VEGETABLE }
 
     it "creates a new Spree::Product and variant" do
+      create(:taxon)
+
       expect(imported_variant).to be_a(Spree::Variant)
+      expect(imported_variant).to be_valid
       expect(imported_variant.id).to be_nil
       expect(imported_variant.semantic_links.size).to eq 1
 
@@ -170,6 +155,7 @@ describe SuppliedProductBuilder do
 
       imported_product = imported_variant.product
       expect(imported_product).to be_a(Spree::Product)
+      expect(imported_product).to be_valid
       expect(imported_product.id).to be_nil
       expect(imported_product.name).to eq("Tomato")
       expect(imported_product.description).to eq("Awesome tomato")