* Do not ingerit array serializer from Serializer

* Tests for ArraySerializer

test/array_serializer_test.rb

@@ -0,0 +1,27 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    class ArraySerializerTest < Minitest::Test
+      def setup
+        @comment = Comment.new
+        @post= Post.new
+        @serializer = ArraySerializer.new([@comment, @post])
+      end
+
+      def test_respond_to_each
+        assert_respond_to @serializer, :each
+      end
+
+      def test_each_object_should_be_serializer_with_appropriate_serializer
+        serializers =  @serializer.to_a
+
+        assert_kind_of CommentSerializer, serializers.first
+        assert_kind_of Comment, serializers.first.object
+
+        assert_kind_of PostSerializer, serializers.last
+        assert_kind_of Post, serializers.last.object
+      end
+    end
+  end
+end