has_one returns arrays with roots pluralized

test/unit/active_model/serializer/has_one_test.rb

@@ -50,7 +50,7 @@ module ActiveModel
         @association.embed = :objects
 
         assert_equal({
-          name: 'Name 1', email: 'mail@server.com', profile: { name: 'N1', description: 'D1' }
+          name: 'Name 1', email: 'mail@server.com', 'profiles' => [{ name: 'N1', description: 'D1' }]
         }, @user_serializer.serializable_hash)
       end
 
@@ -58,7 +58,7 @@ module ActiveModel
         @association.embed = :objects
 
         assert_equal({
-          'user' => { name: 'Name 1', email: 'mail@server.com', profile: { name: 'N1', description: 'D1' } }
+          'user' => { name: 'Name 1', email: 'mail@server.com', 'profiles' => [{ name: 'N1', description: 'D1' }] }
         }, @user_serializer.as_json)
       end
 
@@ -84,7 +84,7 @@ module ActiveModel
         end
 
         assert_equal({
-          'user' => { name: 'Name 1', email: 'mail@server.com', profile: nil }
+          'user' => { name: 'Name 1', email: 'mail@server.com', 'profiles' => [] }
         }, @user_serializer.as_json)
       end
 
@@ -93,7 +93,7 @@ module ActiveModel
         @association.embedded_key = 'root'
 
         assert_equal({
-          name: 'Name 1', email: 'mail@server.com', 'root' => { name: 'N1', description: 'D1' }
+          name: 'Name 1', email: 'mail@server.com', 'root' => [{ name: 'N1', description: 'D1' }]
         }, @user_serializer.serializable_hash)
       end
 
@@ -112,7 +112,7 @@ module ActiveModel
 
         assert_equal({
           'user' => { name: 'Name 1', email: 'mail@server.com', 'profile_id' => @user.profile.object_id },
-          profile: { name: 'N1', description: 'D1' }
+          'profiles' => [{ name: 'N1', description: 'D1' }]
         }, @user_serializer.as_json)
       end
 
@@ -129,7 +129,7 @@ module ActiveModel
 
         assert_equal({
           'user' => { name: 'Name 1', email: 'mail@server.com', 'profile_id' => @user.profile.object_id },
-          profile: { name: 'fake' }
+          'profiles' => [{ name: 'fake' }]
         }, @user_serializer.as_json)
       end
     end