public function testCloneDoubleInvertedIsOriginal()
{
$edgeInverted = $this->edge->createEdgeCloneInverted();
$this->assertInstanceOf(get_class($this->edge), $edgeInverted);
$edge = $edgeInverted->createEdgeCloneInverted();
$this->assertEdgeEquals($this->edge, $edge);
}