public function testAllLeavesStatic()
{
$allLeaves = Cluster::allLeaves()->get();
$this->assertCount(4, $allLeaves);
$leaves = $allLeaves->lists('name');
$this->assertContains('Child 1', $leaves);
$this->assertContains('Child 2.1', $leaves);
$this->assertContains('Child 3', $leaves);
$this->assertContains('Root 2', $leaves);
}