Sets up unit test environment.
Unlike DrupalWebTestCase::setUp(), DrupalUnitTestCase::setUp() does not install modules because tests are performed without accessing the database. Any required files must be explicitly included by the child class setUp() method.
Overrides DrupalUnitTestCase::setUp
function setUp() {
parent::setUp('update');
module_load_include('inc', 'update', 'update.fetch');
}