Make serializer lookup configurable (#1757)

test/action_controller/lookup_proc_test.rb

@@ -0,0 +1,49 @@
+require 'test_helper'
+
+module ActionController
+  module Serialization
+    class LookupProcTest < ActionController::TestCase
+      module Api
+        module V3
+          class PostCustomSerializer < ActiveModel::Serializer
+            attributes :title, :body
+
+            belongs_to :author
+          end
+
+          class AuthorCustomSerializer < ActiveModel::Serializer
+            attributes :name
+          end
+
+          class LookupProcTestController < ActionController::Base
+            def implicit_namespaced_serializer
+              author = Author.new(name: 'Bob')
+              post = Post.new(title: 'New Post', body: 'Body', author: author)
+
+              render json: post
+            end
+          end
+        end
+      end
+
+      tests Api::V3::LookupProcTestController
+
+      test 'implicitly uses namespaced serializer' do
+        controller_namespace = lambda do |resource_class, _parent_serializer_class, namespace|
+          "#{namespace}::#{resource_class}CustomSerializer" if namespace
+        end
+
+        with_prepended_lookup(controller_namespace) do
+          get :implicit_namespaced_serializer
+
+          assert_serializer Api::V3::PostCustomSerializer
+
+          expected = { 'title' => 'New Post', 'body' => 'Body', 'author' => { 'name' => 'Bob' } }
+          actual = JSON.parse(@response.body)
+
+          assert_equal expected, actual
+        end
+      end
+    end
+  end
+end

test/action_controller/namespace_lookup_test.rb

@@ -15,6 +15,16 @@ module ActionController
           end
         end
 
+        module VHeader
+          class BookSerializer < ActiveModel::Serializer
+            attributes :title, :body
+
+            def body
+              'header'
+            end
+          end
+        end
+
         module V3
           class BookSerializer < ActiveModel::Serializer
             attributes :title, :body
@@ -92,6 +102,14 @@ module ActionController
               book = Book.new(title: 'New Post', body: 'Body')
               render json: book
             end
+
+            def namespace_set_by_request_headers
+              book = Book.new(title: 'New Post', body: 'Body')
+              version_from_header = request.headers['X-API_VERSION']
+              namespace = "ActionController::Serialization::NamespaceLookupTest::#{version_from_header}"
+
+              render json: book, namespace: namespace
+            end
           end
         end
       end
@@ -102,6 +120,13 @@ module ActionController
         @test_namespace = self.class.parent
       end
 
+      test 'uses request headers to determine the namespace' do
+        request.env['X-API_VERSION'] = 'Api::VHeader'
+        get :namespace_set_by_request_headers
+
+        assert_serializer Api::VHeader::BookSerializer
+      end
+
       test 'implicitly uses namespaced serializer' do
         get :implicit_namespaced_serializer