How to test which validation failed in ActiveRecord?

Question

I have a model like this:

class User < ActiveRecord::Base   validates_length_of :name, :in => (2..5) end 

I want to test this validation:

it "should not allow too short name" do   u = User.new(:name => "a")   u.valid?   u.should have(1).error_on(:name) end 

But then it does not test which kind of error was set on name. I want to know, if it was too_short, too_long, or maybe some other validation failed.

I can lookup the message text in errors array, like this:

u.errors[:name].should include(I18n.t("activerecord.errors.models.user.attributes.name.too_short")) 

But this will fail when I set activerecord.errors.messages.too_short in locale file instead of model-specific message.

So, is it possible to check which kind of error occured?

Answer 1

Rails added an method to query for errors to ActiveModel in late 2011 and Rails v3.2. Just check to see if the appropriate error has been #added?:

# An error added manually record.errors.add :name, :blank record.errors.added? :name, :blank # => true  # An error added after validation record.email = '[email protected]' record.valid? # => false record.errors.added? :email, :taken, value: '[email protected]' # => true 

Note that for validations that are parametrized (e.g. :greater_than_or_equal_to) you'll need to pass the value of the parameter too.

record.errors.add(:age, :greater_than_or_equal_to, count: 1) record.errors.added?(:age, :greater_than_or_equal_to, count: 1) 

Errors are identified by their i18n key. You can find the appropriate keys to check in the appropriate Rails i18n file for any language under the error section.

Some other nifty questions you can ask ActiveModel#Error are #empty? and #include?(attr), as well as anything you can ask an Enumerable.