gistfile1.rb

class User
  class << self
    def authenticate_for_with_ldap(site, login, password)
      user = authenticate_for_without_ldap(site, login, password)
      if user.nil?
         # Look in LDAP for login, create a local user, and return it.
      end
      user
    end
    alias_method_chain :authenticate_for, :ldap
  end
end

class UserLdapTest << ActiveSupport::TestCase
  test "should use LDAP data to create missing local users" do
    assert_nil User.find_by_login('sam')
    # Mock LDAP interface to return user 'sam' with password 'foo'.
    assert_difference 'User.count', 1 do
      User.authenticate_for sites(:first), 'sam', 'foo'
    end
    @sam = User.find_by_login('sam')
    # Make sure sam has the expected properties.
  end
end