One exception to rule them all

lib/devise/models.rb

@@ -43,13 +43,19 @@ module Devise
     end
 
     def self.check_fields!(klass)
+      failed_attributes = []
+
       klass.devise_modules.each do |mod|
         instance = klass.new
 
         const_get(mod.to_s.classify).required_fields(klass).each do |field|
-          fail Devise::Models::MissingAttribute unless instance.respond_to?(field)
+          failed_attributes << field unless instance.respond_to?(field)
         end
       end
+
+      if failed_attributes.any?
+        fail Devise::Models::MissingAttribute, "The following attributes are missing on your model: #{failed_attributes.join(", ")}"
+      end
     end
 
     # Include the chosen devise modules in your model:

test/models_test.rb

@@ -126,7 +126,7 @@ class CheckFieldsTest < ActiveSupport::TestCase
     end
   end
 
-  test 'raises Devise::Models::MissingAtrribute if the class doesn\'t respond_to one of the attributes' do
+  test 'raises Devise::Models::MissingAtrribute and shows the missing attribute if the class doesn\'t respond_to one of the attributes' do
     Clown = Class.new do
       extend Devise::Models
 
@@ -138,8 +138,23 @@ class CheckFieldsTest < ActiveSupport::TestCase
       attr_accessor :encrypted_password
     end
 
-    assert_raise Devise::Models::MissingAttribute do
+    assert_raise_with_message Devise::Models::MissingAttribute, "The following attributes are missing on your model: email" do
       Devise::Models.check_fields!(Clown)
     end
   end
-end
+
+  test 'raises Devise::Models::MissingAtrribute with all the missing attributes if there is more than one' do
+    Magician = Class.new do
+      extend Devise::Models
+
+      def self.before_validation(instance)
+      end
+
+      devise :database_authenticatable
+    end
+
+    exception = assert_raise_with_message Devise::Models::MissingAttribute, "The following attributes are missing on your model: encrypted_password, email" do
+      Devise::Models.check_fields!(Magician)
+    end
+  end
+end

test/support/assertions.rb

@@ -32,4 +32,12 @@ class ActiveSupport::TestCase
       assert !element.nil?, "the arrays doesn't have the same content"
     end
   end
+
+  def assert_raise_with_message(exception_klass, message)
+    exception = assert_raise exception_klass do
+      yield
+    end
+
+    assert_equal exception.message, message, "The expected message was #{message} but your exception throwed #{exception.message}"
+  end
 end