child example

    $properties = Element::properties($element);

    $this->assertSame(['#property1', '#property2'], $properties);
  }

  /** * Tests the child() method. */
  public function testChild() {
    $this->assertFalse(Element::child('#property'));
    $this->assertTrue(Element::child('property'));
    $this->assertTrue(Element::child('property#'));
  }

  /** * Tests the children() method. */
  public function testChildren() {
    $element = [
      'child2' => ['#weight' => 10],
      'child1' => ['#weight' => 0],