Add prefixItems field to Schema

Based on definition from [1] where it's a list of schemas that defaults
to an empty array

[1]: https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-00#section-10.3.1.1

Author: kevindew

json-schema-for-3.1.md

@@ -81,7 +81,7 @@ then - single schema - done
 else - single schema - done
 dependentSchemas - map of schemas - somewhat complex, is it related to dependentRequired ?
 
-prefixItems: array of schema
+prefixItems: array of schema - done
 items: array of schema - in 3.0
 contains: schema
 

lib/openapi3_parser/node/schema/v3_1.rb

@@ -69,6 +69,11 @@ def then
         def else
           self["else"]
         end
+
+        # @return [Node::Array<Schema>]
+        def prefix_items
+          self["prefixItems"]
+        end
       end
     end
   end

lib/openapi3_parser/node_factory/schema/v3_1.rb

@@ -32,6 +32,7 @@ class V3_1 < NodeFactory::Object # rubocop:disable Naming/ClassAndModuleCamelCas
         field "if", factory: :referenceable_schema
         field "then", factory: :referenceable_schema
         field "else", factory: :referenceable_schema
+        field "prefixItems", factory: :prefix_items_factory
 
         def build_node(data, node_context)
           Node::Schema::V3_1.new(data, node_context)
@@ -77,6 +78,13 @@ def validate_type(validatable)
             validatable.add_error("type must be a string or an array")
           end
         end
+
+        def prefix_items_factory(context)
+          NodeFactory::Array.new(
+            context,
+            value_factory: NodeFactory::Schema.factory(context)
+          )
+        end
       end
     end
   end

spec/lib/openapi3_parser/node_factory/schema/v3_1_spec.rb

@@ -167,4 +167,36 @@
         .with_message('"not a media type" is not a valid media type')
     end
   end
+
+  describe "prefixItems field" do
+    it "is valid with an array with schema values" do
+      instance = described_class.new(
+        create_node_factory_context({ "prefixItems" => [{ "type" => "string" }] })
+      )
+
+      expect(instance).to be_valid
+    end
+
+    it "is invalid for a type other than array" do
+      instance = described_class.new(
+        create_node_factory_context({ "prefixItems" => "string" })
+      )
+
+      expect(instance).not_to be_valid
+      expect(instance)
+        .to have_validation_error("#/prefixItems")
+        .with_message("Invalid type. Expected Array")
+    end
+
+    it "is invalid for values other than objects" do
+      instance = described_class.new(
+        create_node_factory_context({ "prefixItems" => %w[string] })
+      )
+
+      expect(instance).not_to be_valid
+      expect(instance)
+        .to have_validation_error("#/prefixItems/0")
+        .with_message("Invalid type. Expected Object")
+    end
+  end
 end