Fix/enforce initial password length to follow devise

lib/devise_invitable/models.rb

@@ -397,7 +397,8 @@ def after_invitation_accepted(*args, &blk)
           # lower + upper case, a digit and a symbol.
           # For more unusual rules, this method can be overridden.
           def random_password
-            'aA1!' + Devise.friendly_token[0, 20]
+            prefix = 'aA1!'
+            prefix + Devise.friendly_token(self.password_length.last-prefix.length)
           end
       end
     end

test/models/invitable_test.rb

@@ -1,6 +1,10 @@
 require 'test_helper'
 require 'model_tests_helper'
 
+class Validatable < User
+  devise :validatable, password_length: 10..20
+end
+
 class InvitableTest < ActiveSupport::TestCase
 
   def setup
@@ -760,4 +764,10 @@ def assert_callbacks_status(callback, user, fired)
     assert user.persisted?
     assert user.errors.empty?
   end
+
+  test 'should set initial password following devise password_length' do
+    user = Validatable.invite!(email: 'valid@email.com')
+    user.update_attributes(profile_id: 1)
+    assert_empty user.errors
+  end
 end