Private helper method to set the test block's cache mode.
private function setCacheMode($cache_mode) {
db_update('block')
->fields(array(
'cache' => $cache_mode,
))
->condition('module', 'block_test')
->execute();
$current_mode = db_query("SELECT cache FROM {block} WHERE module = 'block_test'")
->fetchField();
if ($current_mode != $cache_mode) {
$this
->fail(t('Unable to set cache mode to %mode. Current mode: %current_mode', array(
'%mode' => $cache_mode,
'%current_mode' => $current_mode,
)));
}
}