/**
* Test VisibleFields and HiddenFields
*/
public function testVisibleAndHiddenFields()
{
$fields = new FieldList(new TextField("A"), new TextField("B"), new HiddenField("C"), new Tabset("Root", new Tab("D", new TextField("D1"), new HiddenField("D2"))));
$hidden = $fields->HiddenFields();
// Inside hidden fields, all HiddenField objects are included, even nested ones
$this->assertNotNull($hidden->dataFieldByName('C'));
$this->assertNotNull($hidden->dataFieldByName('D2'));
// Visible fields are not
$this->assertNull($hidden->dataFieldByName('B'));
$this->assertNull($hidden->dataFieldByName('D1'));
$visible = $fields->VisibleFields();
// Visible fields exclude top level HiddenField objects
$this->assertNotNull($visible->dataFieldByName('A'));
$this->assertNull($visible->dataFieldByName('C'));
// But they don't exclude nested HiddenField objects. This is a limitation; you should
// put all your HiddenFields at the top level.
$this->assertNotNull($visible->dataFieldByName('D2'));
}