public function testApiGetExtension_ReturnsExtension_WhenNodeIsDirectory()
{
$test = $this->getTest();
$fs = $this->createFilesystem();
$p = $this->getPrefixed('DIR_A');
$ext = pathinfo($this->getFullPath('DIR_A'), PATHINFO_EXTENSION);
$test->assertSame($ext, $fs->getExtension($p));
}