public function test_add_query_arg()
{
// Regular tests
$this->assertEquals('/app/admin/users?user=5', util::add_query_arg('user', 5, '/app/admin/users'));
$this->assertEquals('/app/admin/users?user=5', util::add_query_arg(array('user' => 5), '/app/admin/users'));
$this->assertEquals('/app/admin/users?user=5', util::add_query_arg(array('user' => 5), null, '/app/admin/users'));
$this->assertEquals('/app/admin/users?action=edit&user=5', util::add_query_arg('user', 5, '/app/admin/users?action=edit'));
$this->assertEquals('/app/admin/users?action=edit&user=5', util::add_query_arg(array('user' => 5), '/app/admin/users?action=edit'));
$this->assertEquals('/app/admin/users?action=edit&tab=personal&user=5', util::add_query_arg('user', 5, '/app/admin/users?action=edit&tab=personal'));
$this->assertEquals('/app/admin/users?action=edit&tab=personal&user=5', util::add_query_arg(array('user' => 5), '/app/admin/users?action=edit&tab=personal'));
// Ensure strips false.
$this->assertEquals('/index.php', util::add_query_arg('debug', false, '/index.php'));
// With valueless parameters.
$this->assertEquals('/index.php?debug', util::add_query_arg('debug', null, '/index.php'));
$this->assertEquals('/index.php?debug#hash', util::add_query_arg('debug', null, '/index.php#hash'));
// With a URL fragment
$this->assertEquals('/app/admin/users?user=5#test', util::add_query_arg('user', 5, '/app/admin/users#test'));
// Full URL
$this->assertEquals('http://example.com/?a=b', util::add_query_arg('a', 'b', 'http://example.com'));
// Only the query string
$this->assertEquals('?a=b&c=d', util::add_query_arg('c', 'd', '?a=b'));
$this->assertEquals('a=b&c=d', util::add_query_arg('c', 'd', 'a=b'));
// Url encoding test
$this->assertEquals('/app/admin/users?param=containsa%26sym', util::add_query_arg('param', 'containsa&sym', '/app/admin/users'));
// If not provided, grab the URI from the server.
$_SERVER['REQUEST_URI'] = '/app/admin/users';
$this->assertEquals('/app/admin/users?user=6', util::add_query_arg(array('user' => 6)));
$this->assertEquals('/app/admin/users?user=7', util::add_query_arg('user', 7));
}