Validate relatedResource structuredValue titles

lib/cocina/models/validators/description_values_validator.rb

@@ -68,13 +68,17 @@ def validate_values_for_multiples(hash, path)
         end
 
         def validate_title_type(hash, path)
-          # only apply to title.structuredValue with value
-          return unless hash[:value] && path.first == :title && path.include?(:structuredValue)
+          # only apply to title.structuredValue or relatedResource.title.structuredValue with value
+          return unless hash[:value] && (path.first == :title || related_resource_title?(path)) && path.include?(:structuredValue)
 
           # if there is a "value" key, make sure there is also a "type" key, only for title.structuredValue
           error_paths_missing_title_type << path_to_s(path) unless hash[:type]
         end
 
+        def related_resource_title?(path)
+          path.first == :relatedResource && path.third == :title
+        end
+
         def path_to_s(path)
           # This matches the format used by descriptive spreadsheets
           path_str = ''

spec/cocina/models/validators/description_values_validator_spec.rb

@@ -20,7 +20,8 @@
       relatedResource: [
         {
           title: [
-            { value: 'A related title' }
+            { value: 'A related title' },
+            { structuredValue: [{ value: 'A related title', type: 'main title' }]}
           ],
           type: 'related to'
         }
@@ -85,6 +86,23 @@
       }
     end
 
+    let(:related_resource_no_title_type_props) do
+      {
+        title: [
+          { value: 'A title' }
+        ],
+        purl: 'https://purl.stanford.edu/bc123df4567',
+        relatedResource: [
+          {
+            title: [
+              { structuredValue: [{ value: 'A related title'}] }
+            ],
+            type: 'related to'
+          }
+        ]
+      }
+    end
+
     let(:request_desc_props) do
       desc_props.dup.tap do |props|
         props.delete(:purl)
@@ -145,6 +163,16 @@
         end.to raise_error(Cocina::Models::ValidationError, 'Missing type for value in description: title1.structuredValue2')
       end
     end
+
+    describe 'when no type for related resource structured value title in description' do
+      let(:props) { related_resource_no_title_type_props }
+
+      it 'is not valid' do
+        expect do
+          validate
+        end.to raise_error(Cocina::Models::ValidationError, 'Missing type for value in description: relatedResource1.title1.structuredValue1')
+      end
+    end
   end
 
   describe '#meets_preconditions?' do