5 files changed, 29 insertions, 11 deletions
diff --git a/activemodel/CHANGELOG.md b/activemodel/CHANGELOG.md
index 4961d69d2a..3c1510b31d 100644
--- a/activemodel/CHANGELOG.md
+++ b/activemodel/CHANGELOG.md
@@ -1,3 +1,8 @@
+*   Ensure `method_missing` is called for methods passed to
+    `ActiveModel::Serialization#serializable_hash` that don't exist.
+
+    *Jay Elaraj*
+
 *   Add `ActiveModel::Dirty#[attr_name]_previously_changed?` and
     `ActiveModel::Dirty#[attr_name]_previous_change` to improve access
     to recorded changes after the model has been saved.
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index f843b279ce..287a2559d2 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -452,7 +452,6 @@ module ActiveModel
         defaults = []
       end
 
-      defaults << options.delete(:message)
       defaults << :"#{@base.class.i18n_scope}.errors.messages.#{type}" if @base.class.respond_to?(:i18n_scope)
       defaults << :"errors.attributes.#{attribute}.#{type}"
       defaults << :"errors.messages.#{type}"
@@ -461,6 +460,7 @@ module ActiveModel
       defaults.flatten!
 
       key = defaults.shift
+      defaults = options.delete(:message) if options[:message]
       value = (attribute != :base ? @base.send(:read_attribute_for_validation, attribute) : nil)
 
       options = {
diff --git a/activemodel/lib/active_model/serialization.rb b/activemodel/lib/active_model/serialization.rb
index 976f50b13e..c06a64c75f 100644
--- a/activemodel/lib/active_model/serialization.rb
+++ b/activemodel/lib/active_model/serialization.rb
@@ -107,7 +107,7 @@ module ActiveModel
       hash = {}
       attribute_names.each { |n| hash[n] = read_attribute_for_serialization(n) }
 
-      Array(options[:methods]).each { |m| hash[m.to_s] = send(m) if respond_to?(m) }
+      Array(options[:methods]).each { |m| hash[m.to_s] = send(m) }
 
       serializable_add_includes(options) do |association, records, opts|
         hash[association.to_s] = if records.respond_to?(:to_ary)
diff --git a/activemodel/test/cases/errors_test.rb b/activemodel/test/cases/errors_test.rb
index f781a0017f..d10c20caad 100644
--- a/activemodel/test/cases/errors_test.rb
+++ b/activemodel/test/cases/errors_test.rb
@@ -149,6 +149,12 @@ class ErrorsTest < ActiveModel::TestCase
     assert_equal ["cannot be blank"], person.errors[:name]
   end
 
+  test "add an error message on a specific attribute with a defined type" do
+    person = Person.new
+    person.errors.add(:name, :blank, message: "cannot be blank")
+    assert_equal ["cannot be blank"], person.errors[:name]
+  end
+
   test "add an error with a symbol" do
     person = Person.new
     person.errors.add(:name, :blank)
diff --git a/activemodel/test/cases/serialization_test.rb b/activemodel/test/cases/serialization_test.rb
index 4ae41aa19c..8d3165cd78 100644
--- a/activemodel/test/cases/serialization_test.rb
+++ b/activemodel/test/cases/serialization_test.rb
@@ -16,6 +16,14 @@ class SerializationTest < ActiveModel::TestCase
       instance_values.except("address", "friends")
     end
 
+    def method_missing(method_name, *args)
+      if method_name == :bar
+        'i_am_bar'
+      else
+        super
+      end
+    end
+
     def foo
       'i_am_foo'
     end
@@ -58,23 +66,22 @@ class SerializationTest < ActiveModel::TestCase
   end
 
   def test_method_serializable_hash_should_work_with_methods_option
-    expected = {"name"=>"David", "gender"=>"male", "foo"=>"i_am_foo", "email"=>"david@example.com"}
-    assert_equal expected, @user.serializable_hash(methods: [:foo])
+    expected = {"name"=>"David", "gender"=>"male", "foo"=>"i_am_foo", "bar"=>"i_am_bar", "email"=>"david@example.com"}
+    assert_equal expected, @user.serializable_hash(methods: [:foo, :bar])
   end
 
   def test_method_serializable_hash_should_work_with_only_and_methods
-    expected = {"foo"=>"i_am_foo"}
-    assert_equal expected, @user.serializable_hash(only: [], methods: [:foo])
+    expected = {"foo"=>"i_am_foo", "bar"=>"i_am_bar"}
+    assert_equal expected, @user.serializable_hash(only: [], methods: [:foo, :bar])
   end
 
   def test_method_serializable_hash_should_work_with_except_and_methods
-    expected = {"gender"=>"male", "foo"=>"i_am_foo"}
-    assert_equal expected, @user.serializable_hash(except: [:name, :email], methods: [:foo])
+    expected = {"gender"=>"male", "foo"=>"i_am_foo", "bar"=>"i_am_bar"}
+    assert_equal expected, @user.serializable_hash(except: [:name, :email], methods: [:foo, :bar])
   end
 
-  def test_should_not_call_methods_that_dont_respond
-    expected = {"name"=>"David", "gender"=>"male", "email"=>"david@example.com"}
-    assert_equal expected, @user.serializable_hash(methods: [:bar])
+  def test_should_raise_NoMethodError_for_non_existing_method
+    assert_raise(NoMethodError) { @user.serializable_hash(methods: [:nada]) }
   end
 
   def test_should_use_read_attribute_for_serialization