Test that aliases are renamed when duplicates.
function testSelectDuplicateAlias() {
$query = db_select('test', 't');
$alias1 = $query
->addField('t', 'name', 'the_alias');
$alias2 = $query
->addField('t', 'age', 'the_alias');
$this
->assertNotIdentical($alias1, $alias2, 'Duplicate aliases are renamed.');
}