title: When validating ActiveRecord, I'm getting valid? => false but no errors in errors.count. How come?
body: <p>When creating an ActiveRecord in rspec, I use fixtures for valid records.
  But when using the fxitures in tests, they seem to fail validation. 
  In the following example, the employee seems to be perfectly valid, and yet the associated validation in the spec says they are invalid.</p>
  
  <pre><code>class Employee &lt; ActiveRecord::Base
    validates_presence_of     :email
  end
  
  class User &lt; ActiveRecord::Base
    validates_associated      :employee
  end
  
  #Command line debugger in 'debugger' (below) returns:
  Employee.find(745185059).errors.count         # =&gt; 0
  Employee.find(745185059).errors.full_messages # =&gt; []
  Employee.find(745185059).valid?               # =&gt; true
  </code></pre>
  
  <p>For Example:</p>
  
  <pre><code>describe SessionsController do
    fixtures :users, :employees
  
    describe "Logging in by cookie" do
      def set_remember_token token, time
        @user[:remember_token]            = token; 
        @user[:remember_token_expires_at] = time
        debugger
        @user.save! # THIS SAYS THE EMPLOYEE IS INVALID, but why, if the fixtures are good?
      end    
      it 'logs in with cookie' do
        stub!(:cookies).and_return({ :auth_token =&gt; 'hello!' })
        logged_in?.should be_true
      end
    end
  end
  </code></pre>
  
  <p>Any ideas why I get the validation failure?
  (Of course, I cut out a lot of the middle code, it's possible that the error is somewhere else entirely)</p>