In RSpec - how can I test if one attribute is less (or more) than another

In my app I want to have a `Car` model. It will have two fields among others: `date_from` and `date_till` (to specify a period of time someone was using it). And I want the model to validate that date_from should be less or equal than date_till. My model_spec.rb draft looks like this: ``` require 'spec_helper' describe Car do it {should validate_presence_of(:model)} it {should validate_presence_of(:made)} it "should have date_till only if it has date_from" its "date_till should be >= date_from" end ``` Obviously, I can just write a "long" test where I will try to set date_till to be greater than date_from - and the model just should be invalid. But maybe there are some elegant ways to do it? So, how can I (using RSpec matchers) validate that one field is not greater than another? upd: I looked at @itsnikolay's answer and coded it like that: ``` it "does not allow date_till less than date_from" do subject.date_from = Date.today subject.date_till = Date.today - 1.day subject.valid?.should be_false end ``` Had to do it without matchers. Well, not a tragedy :)