public function testMap()
{
$root = new RootNode();
$parent_one = $this->createParentNode();
$parent_one->appendTo($root);
$one = $this->createNode();
$one->appendTo($parent_one);
$parent_two = $this->createParentNode();
$parent_two->appendTo($root);
$first = $this->createNode();
$first->appendTo($parent_two);
$collection = new NodeCollection([$parent_one, $parent_two], FALSE);
$map = $collection->map(function (ParentNode $node) {
return $node->firstChild();
});
$this->assertCount(2, $map);
$this->assertSame($one, $map[0]);
$this->assertSame($first, $map[1]);
}
