Autotest fails to recognize spec

department.rb

class Department < ActiveRecord::Base
  belongs_to :company
  validates_presence_of :name, :department_number
end

department_spec.rb

require 'spec_helper'

describe Department do

it {should belong_to(:company)}

[:name, :department_number].each do |attr|
  it "must have a(n) #{attr}" do
    d = Factory.build(:department, attr.to_s => nil)
    d.should_not be_valid
    d.errors[attr].should_not be_empty
  end
end

end

Output from autotest -v when department.rb changes

[["app/models/department.rb", Wed Jun 29 13:10:07 -0600 2011]]
No tests matched app/models/dealership.rb
[["app/models/department.rb", Wed Jun 29 13:10:07 -0600 2011]]
No tests matched app/models/department.rb