Test distinct queries.
function testDistinct() {
$query = db_select('test_task');
$task_field = $query
->addField('test_task', 'task');
$query
->distinct();
$result = $query
->execute();
$num_records = 0;
foreach ($result as $record) {
$num_records++;
}
$this
->assertEqual($num_records, 6, 'Returned the correct number of rows.');
}