public function testDefaultClasses()
 {
     Form::config()->update('default_classes', array('class1'));
     $form = $this->getStubForm();
     $this->assertContains('class1', $form->extraClass(), 'Class list does not contain expected class');
     Form::config()->update('default_classes', array('class1', 'class2'));
     $form = $this->getStubForm();
     $this->assertContains('class1 class2', $form->extraClass(), 'Class list does not contain expected class');
     Form::config()->update('default_classes', array('class3'));
     $form = $this->getStubForm();
     $this->assertContains('class3', $form->extraClass(), 'Class list does not contain expected class');
     $form->removeExtraClass('class3');
     $this->assertNotContains('class3', $form->extraClass(), 'Class list contains unexpected class');
 }