Give prelude unit a type of empty structure

Author: Matt Muller

gems/smithy-cbor/lib/smithy-cbor/deserializer.rb

@@ -53,9 +53,7 @@ def map(ref, values, target = nil)
         target
       end
 
-      def structure(ref, values, target = nil) # rubocop:disable Metrics/AbcSize
-        return Schema::EmptyStructure.new if ref.shape == Prelude::Unit
-
+      def structure(ref, values, target = nil)
         target = ref.shape.type.new if target.nil?
         ref.shape.members.each do |member_name, member_ref|
           value = values[member_ref.member_name]

gems/smithy-json/lib/smithy-json/deserializer.rb

@@ -68,12 +68,10 @@ def map(ref, values, target = nil)
 
       def structure(ref, values, target = nil) # rubocop:disable Metrics/AbcSize
         return if values.nil?
-        return Smithy::Schema::EmptyStructure.new if ref.shape == Prelude::Unit
 
         target = ref.shape.type.new if target.nil?
         ref.shape.members.each do |member_name, member_ref|
-          key = member_ref.traits['smithy.api#jsonName'] || member_ref.member_name
-          value = values[key]
+          value = values[location_name(member_ref)]
           value = default(member_ref) if value.nil? && default?(member_ref.traits)
           next if value.nil?
 
@@ -104,7 +102,7 @@ def union(ref, values, target = nil) # rubocop:disable Metrics/AbcSize
         return nil if key.nil?
 
         ref.shape.members.each do |member_name, member_ref|
-          name = member_ref.traits['smithy.api#jsonName'] || member_ref.member_name
+          name = location_name(member_ref)
           next unless values.key?(name)
 
           target = ref.shape.member_type(member_name) if target.nil?
@@ -113,20 +111,23 @@ def union(ref, values, target = nil) # rubocop:disable Metrics/AbcSize
         ref.shape.member_type(:unknown).new(key, value)
       end
 
-      def sanitize_union!(ref, values) # rubocop:disable Metrics/CyclomaticComplexity
+      def sanitize_union!(ref, values)
         return unless values.size > 1
 
         # __type should be ignored unless it's a jsonName for a member
         type_as_name = false
         ref.shape.members.each_value do |member_ref|
-          name = member_ref.traits['smithy.api#jsonName'] || member_ref.member_name
-          type_as_name = true if name == '__type'
+          type_as_name = true if location_name(member_ref) == '__type'
         end
 
         values.delete('__type') if values.key?('__type') && !type_as_name
         raise ArgumentError, "union value includes more than one key, received: #{values.keys}" if values.size > 1
       end
 
+      def location_name(ref)
+        ref.traits['smithy.api#jsonName'] || ref.member_name
+      end
+
       def sparse?(shape)
         shape.traits.include?('smithy.api#sparse')
       end

gems/smithy-schema/lib/smithy-schema.rb

@@ -1,8 +1,8 @@
 # frozen_string_literal: true
 
-require_relative 'smithy-schema/shapes'
 require_relative 'smithy-schema/structure'
 require_relative 'smithy-schema/union'
+require_relative 'smithy-schema/shapes'
 
 module Smithy
   # Base module for Smithy schema classes.

gems/smithy-schema/lib/smithy-schema/shapes.rb

@@ -201,6 +201,11 @@ class StringShape < Shape; end
 
       # Represents a Structure shape.
       class StructureShape < Structure
+        def initialize(options = {})
+          super
+          @type = options[:type]
+        end
+
         # @return [Class]
         attr_accessor :type
       end
@@ -302,7 +307,8 @@ module Prelude
         Timestamp = TimestampShape.new(id: 'smithy.api#Timestamp')
         Unit = StructureShape.new(
           id: 'smithy.api#Unit',
-          traits: { 'smithy.api#unitType' => {} }
+          traits: { 'smithy.api#unitType' => {} },
+          type: Schema::EmptyStructure
         )
       end
     end