5 files changed, 17 insertions, 4 deletions
diff --git a/activemodel/activemodel.gemspec b/activemodel/activemodel.gemspec
index e5075485bb..260ad01b65 100644
--- a/activemodel/activemodel.gemspec
+++ b/activemodel/activemodel.gemspec
@@ -19,5 +19,4 @@ Gem::Specification.new do |s|
   s.add_dependency('activesupport', version)
   s.add_dependency('builder',       '~> 3.0.0')
   s.add_dependency('i18n',          '~> 0.6')
-  s.add_dependency('bcrypt-ruby',   '~> 3.0.0')
 end
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index e3e71525fa..166cccf161 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -29,7 +29,7 @@ module ActiveModel
   #
   #     include ActiveModel::Dirty
   #
-  #     define_attribute_methods = [:name]
+  #     define_attribute_methods [:name]
   #
   #     def name
   #       @name
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index 843c0c3cb5..7828434927 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -88,6 +88,7 @@ module ActiveModel
     def include?(error)
       (v = messages[error]) && v.any?
     end
+    alias :has_key? :include?
 
     # Get messages for +key+
     def get(key)
diff --git a/activemodel/lib/active_model/secure_password.rb b/activemodel/lib/active_model/secure_password.rb
index 63380d6ffd..7a109d9a52 100644
--- a/activemodel/lib/active_model/secure_password.rb
+++ b/activemodel/lib/active_model/secure_password.rb
@@ -1,5 +1,3 @@
-require 'bcrypt'
-
 module ActiveModel
   module SecurePassword
     extend ActiveSupport::Concern
@@ -12,6 +10,10 @@ module ActiveModel
       # a "password_confirmation" attribute) are automatically added.
       # You can add more validations by hand if need be.
       #
+      # You need to add bcrypt-ruby (~> 3.0.0) to Gemfile to use has_secure_password:
+      #
+      #   gem 'bcrypt-ruby', '~> 3.0.0'
+      #
       # Example using Active Record (which automatically includes ActiveModel::SecurePassword):
       #
       #   # Schema: User(name:string, password_digest:string)
@@ -30,6 +32,11 @@ module ActiveModel
       #   User.find_by_name("david").try(:authenticate, "notright")      # => nil
       #   User.find_by_name("david").try(:authenticate, "mUc3m00RsqyRe") # => user
       def has_secure_password
+        # Load bcrypt-ruby only when has_secured_password is used to avoid make ActiveModel
+        # (and by extension the entire framework) dependent on a binary library.
+        gem 'bcrypt-ruby', '~> 3.0.0'
+        require 'bcrypt'
+
         attr_reader :password
 
         validates_confirmation_of :password
diff --git a/activemodel/test/cases/errors_test.rb b/activemodel/test/cases/errors_test.rb
index 85ca8ca835..da109a8738 100644
--- a/activemodel/test/cases/errors_test.rb
+++ b/activemodel/test/cases/errors_test.rb
@@ -33,6 +33,12 @@ class ErrorsTest < ActiveModel::TestCase
     assert errors.include?(:foo), 'errors should include :foo'
   end
 
+  def test_has_key?
+    errors = ActiveModel::Errors.new(self)
+    errors[:foo] = 'omg'
+    assert errors.has_key?(:foo), 'errors should have key :foo'
+  end
+
   test "should return true if no errors" do
     person = Person.new
     person.errors[:foo]