5 files changed, 16 insertions, 9 deletions
diff --git a/activemodel/lib/active_model/callbacks.rb b/activemodel/lib/active_model/callbacks.rb
index eac2761433..835e6f7716 100644
--- a/activemodel/lib/active_model/callbacks.rb
+++ b/activemodel/lib/active_model/callbacks.rb
@@ -56,6 +56,9 @@ module ActiveModel
   #
   # Would only create the +after_create+ and +before_create+ callback methods in
   # your class.
+  #
+  # NOTE: Calling the same callback multiple times will overwrite previous callback definitions.
+  #
   module Callbacks
     def self.extended(base) #:nodoc:
       base.class_eval do
diff --git a/activemodel/lib/active_model/validations.rb b/activemodel/lib/active_model/validations.rb
index d460068830..1f14a068d1 100644
--- a/activemodel/lib/active_model/validations.rb
+++ b/activemodel/lib/active_model/validations.rb
@@ -147,6 +147,9 @@ module ActiveModel
       #   or <tt>unless: Proc.new { |user| user.signup_step <= 2 }</tt>). The
       #   method, proc or string should return or evaluate to a +true+ or +false+
       #   value.
+      #
+      # NOTE: Calling +validate+ multiple times on the same method will overwrite previous definitions.
+      #
       def validate(*args, &block)
         options = args.extract_options!
 
@@ -432,4 +435,4 @@ module ActiveModel
   end
 end
 
-Dir[File.dirname(__FILE__) + "/validations/*.rb"].each { |file| require file }
+Dir[File.expand_path("validations/*.rb", __dir__)].each { |file| require file }
diff --git a/activemodel/lib/active_model/validations/numericality.rb b/activemodel/lib/active_model/validations/numericality.rb
index b82c85ddf4..fb053a4c4e 100644
--- a/activemodel/lib/active_model/validations/numericality.rb
+++ b/activemodel/lib/active_model/validations/numericality.rb
@@ -36,7 +36,9 @@ module ActiveModel
           return
         end
 
-        unless raw_value.is_a?(Numeric)
+        if raw_value.is_a?(Numeric)
+          value = raw_value
+        else
           value = parse_raw_value_as_a_number(raw_value)
         end
 
diff --git a/activemodel/lib/active_model/validations/validates.rb b/activemodel/lib/active_model/validations/validates.rb
index 0ce5935f3a..a8b958e974 100644
--- a/activemodel/lib/active_model/validations/validates.rb
+++ b/activemodel/lib/active_model/validations/validates.rb
@@ -18,7 +18,6 @@ module ActiveModel
       #   validates :first_name, length: { maximum: 30 }
       #   validates :age, numericality: true
       #   validates :username, presence: true
-      #   validates :username, uniqueness: true
       #
       # The power of the +validates+ method comes when using custom validators
       # and default validators in one call for a given attribute.
@@ -34,7 +33,7 @@ module ActiveModel
       #     include ActiveModel::Validations
       #     attr_accessor :name, :email
       #
-      #     validates :name, presence: true, uniqueness: true, length: { maximum: 100 }
+      #     validates :name, presence: true, length: { maximum: 100 }
       #     validates :email, presence: true, email: true
       #   end
       #
@@ -94,7 +93,7 @@ module ActiveModel
       # Example:
       #
       #   validates :password, presence: true, confirmation: true, if: :password_required?
-      #   validates :token, uniqueness: true, strict: TokenGenerationException
+      #   validates :token, length: 24, strict: TokenLengthException
       #
       #
       # Finally, the options +:if+, +:unless+, +:on+, +:allow_blank+, +:allow_nil+, +:strict+
diff --git a/activemodel/lib/active_model/validator.rb b/activemodel/lib/active_model/validator.rb
index 98234e9b6b..6c11981e1d 100644
--- a/activemodel/lib/active_model/validator.rb
+++ b/activemodel/lib/active_model/validator.rb
@@ -82,7 +82,7 @@ module ActiveModel
   #   end
   #
   # It can be useful to access the class that is using that validator when there are prerequisites such
-  # as an +attr_accessor+ being present. This class is accessible via +options[:class]+ in the constructor.
+  # as an +attr_accessor+ being present. This class is accessible via <tt>options[:class]</tt> in the constructor.
   # To setup your validator override the constructor.
   #
   #   class MyValidator < ActiveModel::Validator
@@ -97,7 +97,7 @@ module ActiveModel
     # Returns the kind of the validator.
     #
     #   PresenceValidator.kind   # => :presence
-    #   UniquenessValidator.kind # => :uniqueness
+    #   AcceptanceValidator.kind # => :acceptance
     def self.kind
       @kind ||= name.split("::").last.underscore.chomp("_validator").to_sym unless anonymous?
     end
@@ -109,8 +109,8 @@ module ActiveModel
 
     # Returns the kind for this validator.
     #
-    #   PresenceValidator.new.kind   # => :presence
-    #   UniquenessValidator.new.kind # => :uniqueness
+    #   PresenceValidator.new(attributes: [:username]).kind # => :presence
+    #   AcceptanceValidator.new(attributes: [:terms]).kind  # => :acceptance
     def kind
       self.class.kind
     end