Add scenario to test coercion of grape entity

lib/grape/validations/types/build_coercer.rb

@@ -3,6 +3,7 @@
 require_relative 'array_coercer'
 require_relative 'set_coercer'
 require_relative 'primitive_coercer'
+require_relative 'grape_entity_coercer'
 
 module Grape
   module Validations
@@ -64,6 +65,8 @@ def self.create_coercer_instance(type, method, strict)
           ArrayCoercer.new type, strict
         elsif type.is_a?(Set)
           SetCoercer.new type, strict
+        elsif type.superclass == Grape::Entity
+          GrapeEntityCoercer.new type
         else
           PrimitiveCoercer.new type, strict
         end

lib/grape/validations/types/grape_entity_coercer.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Grape
+  module Validations
+    module Types
+      # Handles coercion and type checking for parameters that are subclasses
+      # of Grape::Entity.
+      class GrapeEntityCoercer
+        def initialize(type)
+          @type = type
+        end
+
+        def call(val)
+          return if val.nil?
+
+          if val.is_a?(Array)
+            val.each do |i|
+              return InvalidValue.new unless coerced?(i)
+            end
+          else
+            return InvalidValue.new unless coerced?(val)
+          end
+        end
+
+        private
+
+        attr_reader :type
+
+        def coerced?(val)
+          val.each_key do |k|
+            return false unless exposure_keys.include?(k.to_sym)
+          end
+
+          true
+        end
+
+        def exposure_keys
+          type.root_exposures.map(&:key)
+        end
+      end
+    end
+  end
+end

spec/grape/validations/validators/coerce_spec.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'spec_helper'
+require 'grape_entity'
 
 describe Grape::Validations::CoerceValidator do
   subject do
@@ -984,5 +985,64 @@ def self.parsed?(value)
         10.times { get '/' }
       end
     end
+
+    context 'grape entity' do
+      class Name < Grape::Entity
+        expose :first_name, documentation: { required: true, type: 'String', desc: 'first name' }
+        expose :surname, as: 'lastName', documentation: { required: true, type: 'String', desc: 'last name' }
+      end
+
+      class Person < Grape::Entity
+        expose :email, documentation: { required: true, type: 'String', desc: 'email address' }
+        expose :name, using: Name, documentation: { required: true, type: 'Name', desc: 'full name' }
+      end
+
+      class Question < Grape::Entity
+        expose :order, documentation: { required: true, type: 'Integer', desc: 'order of question' }
+        expose :text, documentation: { required: true, type: 'String', desc: 'text of question' }
+      end
+
+      it 'handles a subclass of Grape::Entity' do
+        subject.params do
+          requires :name, type: Name
+        end
+        subject.get '/' do
+          'simple grape entity works'
+        end
+
+        get '/', name: { first_name: 'John', 'lastName' => 'Smith' }
+
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('simple grape entity works')
+      end
+
+      it 'handles a subclass of Grape::Entity which exposes another Grape::Entity' do
+        subject.params do
+          requires :person, type: Person
+        end
+        subject.get '/' do
+          'complex grape entity works'
+        end
+
+        get '/', person: { email: 'john@example.com', name: { first_name: 'John', 'lastName' => 'Smith' } }
+
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('complex grape entity works')
+      end
+
+      it 'handles an array of elements of a subclass of Grape::Entity' do
+        subject.params do
+          requires :question, type: Question
+        end
+        subject.get '/' do
+          'an array of grape entities works'
+        end
+
+        get '/', question: [{ order: 1, text: 'Why?' }, { order: 2, text: 'How?' }]
+
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('an array of grape entities works')
+      end
+    end
   end
 end