AdamWathan\Form\Elements\Checkbox::defaultToChecked PHP Method

    public function defaultToChecked()
    {
        if (!isset($this->checked) && is_null($this->oldValue)) {
            $this->check();
        }
        return $this;
    }

 public function testDefaultToChecked()
 {
     $checkbox = new Checkbox('above_18');
     $expected = '<input type="checkbox" name="above_18" value="1" checked="checked">';
     $result = $checkbox->defaultToChecked()->render();
     $this->assertEquals($expected, $result);
     $checkbox = new Checkbox('above_18');
     $expected = '<input type="checkbox" name="above_18" value="1">';
     $result = $checkbox->defaultToChecked()->uncheck()->render();
     $this->assertEquals($expected, $result);
     $checkbox = new Checkbox('above_18');
     $expected = '<input type="checkbox" name="above_18" value="1">';
     $result = $checkbox->uncheck()->defaultToChecked()->render();
     $this->assertEquals($expected, $result);
 }