Merge branch 'master' into mrbrdo-fixserialization

* master: (142 commits)
  Use Colspan in th Tags
  Added test for link_to_unless to make sure the result consistency.
  Escape the string even when the condition of link_to_unless is not satisfied.
  Add CHANGELOG entry for #10969
  Use a case insensitive URI Regexp for #asset_path
  collection tags accept html attributes as the last element of collection
  Rewind StringIO instances before be parsed again
  Use xml instead already parsed xml
  Updated the doc for const_regexp [ci skip]
  Make test name descriptive and add reference to original regression commit
  fixture setup does not rely on `AR::Base.configurations`.
  regression test + mysql2 adapter raises correct error if conn is closed.
  cleanup, remove trailing whitespace from AR changelog
  'json' gem is no more required under JRuby
  fix typos
  Fix AS changelog [ci skip]
  Update the HTML boolean attributes per the HTML 5.1 spec
  Changing const_regexp to check for constant name.
  valid_app_const? -> valid_const?
  Add CHANGELOG entry for #10740
  ...

4 files changed, 18 insertions, 14 deletions

diff --git a/activemodel/lib/active_model/callbacks.rb b/activemodel/lib/active_model/callbacks.rb
index 8b09f8b203..377aa6ee27 100644
--- a/activemodel/lib/active_model/callbacks.rb
+++ b/activemodel/lib/active_model/callbacks.rb
@@ -135,7 +135,10 @@ module ActiveModel
       klass.define_singleton_method("after_#{callback}") do |*args, &block|
         options = args.extract_options!
         options[:prepend] = true
-        options[:if] = Array(options[:if]) << "value != false"
+        conditional = ActiveSupport::Callbacks::Conditionals::Value.new { |v|
+          v != false
+        }
+        options[:if] = Array(options[:if]) << conditional
         set_callback(:"#{callback}", :after, *(args << options), &block)
       end
     end
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index cafdb946c0..ea5ddf71de 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -142,23 +142,23 @@ module ActiveModel
       @changed_attributes ||= {}
     end
 
-    private
+    # Handle <tt>*_changed?</tt> for +method_missing+.
+    def attribute_changed?(attr)
+      changed_attributes.include?(attr)
+    end
 
-      # Handle <tt>*_changed?</tt> for +method_missing+.
-      def attribute_changed?(attr)
-        changed_attributes.include?(attr)
-      end
+    # Handle <tt>*_was</tt> for +method_missing+.
+    def attribute_was(attr)
+      attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
+    end
+
+    private
 
       # Handle <tt>*_change</tt> for +method_missing+.
       def attribute_change(attr)
         [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
       end
 
-      # Handle <tt>*_was</tt> for +method_missing+.
-      def attribute_was(attr)
-        attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
-      end
-
       # Handle <tt>*_will_change!</tt> for +method_missing+.
       def attribute_will_change!(attr)
         return if attribute_changed?(attr)
diff --git a/activemodel/lib/active_model/serializers/json.rb b/activemodel/lib/active_model/serializers/json.rb
index 9d984b7a18..05e2e089e5 100644
--- a/activemodel/lib/active_model/serializers/json.rb
+++ b/activemodel/lib/active_model/serializers/json.rb
@@ -109,7 +109,7 @@ module ActiveModel
       #
       #     def attributes=(hash)
       #       hash.each do |key, value|
-      #         instance_variable_set("@#{key}", value)
+      #         send("#{key}=", value)
       #       end
       #     end
       #
diff --git a/activemodel/lib/active_model/validations.rb b/activemodel/lib/active_model/validations.rb
index 92206450d2..31c2245265 100644
--- a/activemodel/lib/active_model/validations.rb
+++ b/activemodel/lib/active_model/validations.rb
@@ -142,7 +142,9 @@ module ActiveModel
         if options.key?(:on)
           options = options.dup
           options[:if] = Array(options[:if])
-          options[:if].unshift("validation_context == :#{options[:on]}")
+          options[:if].unshift lambda { |o|
+            o.validation_context == options[:on]
+          }
         end
         args << options
         set_callback(:validate, *args, &block)
@@ -226,7 +228,6 @@ module ActiveModel
       #   Person.validators_on(:name)
       #   # => [
       #   #       #<ActiveModel::Validations::PresenceValidator:0x007fe604914e60 @attributes=[:name], @options={}>,
-      #   #       #<ActiveModel::Validations::InclusionValidator:0x007fe603bb8780 @attributes=[:age], @options={in:0..99}>
       #   #    ]
       def validators_on(*attributes)
         attributes.flat_map do |attribute|