Fix infinite recursion

The method for testing whether to include an association was causing
an infinite loop when two models referenced each other.

lib/active_model/serializer/adapter/json_api.rb

@@ -83,11 +83,9 @@ module ActiveModel
             @top[:linked][plural_name].push attrs unless @top[:linked][plural_name].include? attrs
           end
 
-          unless serializer.respond_to?(:each)
+          serializer.each_association do |name, association, opts|
-            serializer.each_association do |name, association, opts|
+            add_linked(name, association, resource_path) if association
-              add_linked(name, association, resource) if association
+          end if include_nested_assoc? resource_path
-            end
-          end
         end
 
         private
@@ -98,8 +96,20 @@ module ActiveModel
           attributes
         end
 
-        def include_assoc? assoc
+        def include_assoc?(assoc)
-          @options[:include] && @options[:include].split(',').include?(assoc.to_s)
+          return false unless @options[:include]
+          check_assoc("#{assoc}$")
+        end
+
+        def include_nested_assoc?(assoc)
+          return false unless @options[:include]
+          check_assoc("#{assoc}.")
+        end
+
+        def check_assoc(assoc)
+          @options[:include].split(',').any? do |s|
+            s.match(/^#{assoc.gsub('.', '\.')}/)
+          end
         end
       end
     end

test/action_controller/json_api_linked_test.rb

@@ -7,8 +7,10 @@ module ActionController
         def setup_post
           @author = Author.new(id: 1, name: 'Steve K.')
           @author.posts = []
+          @author.bio = nil
           @author2 = Author.new(id: 2, name: 'Anonymous')
           @author2.posts = []
+          @author2.bio = nil
           @post = Post.new(id: 1, title: 'New Post', body: 'Body')
           @first_comment = Comment.new(id: 1, body: 'ZOMG A COMMENT')
           @second_comment = Comment.new(id: 2, body: 'ZOMG ANOTHER COMMENT')

test/adapter/json_api/belongs_to_test.rb

@@ -7,6 +7,7 @@ module ActiveModel
         class BelongsToTest < Minitest::Test
           def setup
             @author = Author.new(id: 1, name: 'Steve K.')
+            @author.bio = nil
             @post = Post.new(id: 42, title: 'New Post', body: 'Body')
             @anonymous_post = Post.new(id: 43, title: 'Hello!!', body: 'Hello, world!!')
             @comment = Comment.new(id: 1, body: 'ZOMG A COMMENT')

test/adapter/json_api/collection_test.rb

@@ -7,6 +7,7 @@ module ActiveModel
         class CollectionTest < Minitest::Test
           def setup
             @author = Author.new(id: 1, name: 'Steve K.')
+            @author.bio = nil
             @first_post = Post.new(id: 1, title: 'Hello!!', body: 'Hello, world!!')
             @second_post = Post.new(id: 2, title: 'New Post', body: 'Body')
             @first_post.comments = []

test/adapter/json_api/has_many_embed_ids_test.rb

@@ -7,6 +7,7 @@ module ActiveModel
         class HasManyEmbedIdsTest < Minitest::Test
           def setup
             @author = Author.new(name: 'Steve K.')
+            @author.bio = nil
             @first_post = Post.new(id: 1, title: 'Hello!!', body: 'Hello, world!!')
             @second_post = Post.new(id: 2, title: 'New Post', body: 'Body')
             @author.posts = [@first_post, @second_post]

test/adapter/json_api/has_many_test.rb

@@ -8,6 +8,7 @@ module ActiveModel
           def setup
             @author = Author.new(id: 1, name: 'Steve K.')
             @author.posts = []
+            @author.bio = nil
             @post = Post.new(id: 1, title: 'New Post', body: 'Body')
             @post_without_comments = Post.new(id: 2, title: 'Second Post', body: 'Second')
             @first_comment = Comment.new(id: 1, body: 'ZOMG A COMMENT')

test/adapter/json_api/linked_test.rb

@@ -7,6 +7,7 @@ module ActiveModel
         class LinkedTest < Minitest::Test
           def setup
             @author = Author.new(id: 1, name: 'Steve K.')
+            @bio = Bio.new(id: 1, content: 'AMS Contributor')
             @first_post = Post.new(id: 1, title: 'Hello!!', body: 'Hello, world!!')
             @second_post = Post.new(id: 2, title: 'New Post', body: 'Body')
             @first_post.comments = []
@@ -14,9 +15,11 @@ module ActiveModel
             @first_post.author = @author
             @second_post.author = @author
             @author.posts = [@first_post, @second_post]
+            @author.bio = @bio
+            @bio.author = @author
 
             @serializer = ArraySerializer.new([@first_post, @second_post])
-            @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer, include: 'author,comments')
+            @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer, include: 'author,author.bio,comments')
           end
 
           def test_include_multiple_posts_and_linked
@@ -31,7 +34,10 @@ module ActiveModel
                            { title: "Hello!!", body: "Hello, world!!", id: "1", links: { comments: ['1', '2'], author: "1" } },
                            { title: "New Post", body: "Body", id: "2", links: { comments: [], :author => "1" } }
                          ], @adapter.serializable_hash[:posts])
-            assert_equal({ :comments => [{ :id => "1", :body => "ZOMG A COMMENT" }, { :id => "2", :body => "ZOMG ANOTHER COMMENT" }], :authors => [{ :id => "1", :name => "Steve K." }] }, @adapter.serializable_hash[:linked])
+            assert_equal({ :comments => [{ :id => "1", :body => "ZOMG A COMMENT" },
+                                         { :id => "2", :body => "ZOMG ANOTHER COMMENT" }],
+                           :authors => [{ :id => "1", :name => "Steve K." }],
+                           :bios=>[{:id=>"1", :content=>"AMS Contributor"}] }, @adapter.serializable_hash[:linked])
           end
         end
       end

test/fixtures/poro.rb

@@ -38,6 +38,7 @@ end
 Post = Class.new(Model)
 Comment = Class.new(Model)
 Author = Class.new(Model)
+Bio = Class.new(Model)
 Blog = Class.new(Model)
 
 PostSerializer = Class.new(ActiveModel::Serializer) do
@@ -59,6 +60,13 @@ AuthorSerializer = Class.new(ActiveModel::Serializer) do
   attributes :id, :name
 
   has_many :posts, embed: :ids
+  belongs_to :bio
+end
+
+BioSerializer = Class.new(ActiveModel::Serializer) do
+  attributes :id, :content
+
+  belongs_to :author
 end
 
 BlogSerializer = Class.new(ActiveModel::Serializer) do

test/serializers/associations_test.rb

@@ -26,6 +26,7 @@ module ActiveModel
 
       def setup
         @author = Author.new(name: 'Steve K.')
+        @author.bio = nil
         @post = Post.new({ title: 'New Post', body: 'Body' })
         @comment = Comment.new({ id: 1, body: 'ZOMG A COMMENT' })
         @post.comments = [@comment]
@@ -39,11 +40,21 @@ module ActiveModel
       end
 
       def test_has_many
-        assert_equal({posts: {type: :has_many, options: {embed: :ids}}}, @author_serializer.class._associations)
+        assert_equal(
+          { posts: { type: :has_many, options: { embed: :ids } },
+            bio: { type: :belongs_to, options: {} } },
+          @author_serializer.class._associations
+        )
         @author_serializer.each_association do |name, serializer, options|
-          assert_equal(:posts, name)
+          if name == :posts
-          assert_equal({embed: :ids}, options)
+            assert_equal({embed: :ids}, options)
-          assert_kind_of(ActiveModel::Serializer.config.array_serializer, serializer)
+            assert_kind_of(ActiveModel::Serializer.config.array_serializer, serializer)
+          elsif name == :bio
+            assert_equal({}, options)
+            assert_nil serializer
+          else
+            flunk "Unknown association: #{name}"
+          end
         end
       end