public function testDefaultClasses()
 {
     Config::nest();
     FormField::config()->update('default_classes', array('class1'));
     $field = new FormField('MyField');
     $this->assertContains('class1', $field->extraClass(), 'Class list does not contain expected class');
     FormField::config()->update('default_classes', array('class1', 'class2'));
     $field = new FormField('MyField');
     $this->assertContains('class1 class2', $field->extraClass(), 'Class list does not contain expected class');
     FormField::config()->update('default_classes', array('class3'));
     $field = new FormField('MyField');
     $this->assertContains('class3', $field->extraClass(), 'Class list does not contain expected class');
     $field->removeExtraClass('class3');
     $this->assertNotContains('class3', $field->extraClass(), 'Class list contains unexpected class');
     TextField::config()->update('default_classes', array('textfield-class'));
     $field = new TextField('MyField');
     //check default classes inherit
     $this->assertContains('class3', $field->extraClass(), 'Class list does not contain inherited class');
     $this->assertContains('textfield-class', $field->extraClass(), 'Class list does not contain expected class');
     Config::unnest();
 }