TabBarView({Key key, @required List<Widget> children })

Creates a widget that displays the contents of a tab.

The children argument must not be null and must not be empty.

Source 

TabBarView({
  Key key,
  @required List<Widget> children
}) : super(
  key: key,
  scrollDirection: Axis.horizontal,
  children: children
) {
  assert(children != null);
  assert(children.length > 1);
}