add index and show for object type

spec/acceptance/object_types_spec.rb

+require 'acceptance_helpers'
+
+resource 'Object Type' do
+  header 'Accept', 'application/json'
+  header 'Content-Type', 'application/json'
+
+  let(:object_types) { ObjectType.all }
+
+  get '/v1/object_types' do
+    parameter :limit, 'Limit of object types'
+    parameter :offset, 'Offset of object types'
+
+    let(:limit) { 12 }
+    let(:offset) { 0 }
+
+    example_request 'Get a list of object types' do
+      # active model serializer may render model associations in different order for collections (array of items), so we're verifing only returned ids
+      expect(JSON.parse(response_body).map { |o| o['id'] }.sort).to eq(ObjectType.limit(limit).offset(offset).pluck(:id).sort)
+      expect(status).to eq(200)
+    end
+  end
+
+  get '/v1/object_types/:id' do
+    let(:id) { object_types.first.id }
+
+    example 'Get an object type' do
+      do_request
+      expect(path).to eq("/v1/object_types/#{id}") # `:id` is replaced with the value of `id`
+      expect(response_body).to eq(Helper.serialize(ObjectType.find(id)))
+      expect(status).to eq(200)
+    end
+  end
+
+end