What is a widget test in Flutter, and how does it genuinely differ from a unit test in terms of verifying that a specific given widget actually genuinely renders and behaves correctly?

A widget test verifies that a specific given widget properly renders correctly and correctly responds to genuine user interaction, running in a genuinely simulated lightweight test environment rather than on an actual real device, and unlike a unit test which genuinely verifies just a single isolated piece of logic, a widget test genuinely exercises the actual real widget building and rendering pipeline, letting you verify things like whether a specific expected piece of text actually genuinely appears on screen or whether tapping a specific given button actually properly triggers the genuinely correct expected resulting behavior.

testWidgets('displays greeting text', (tester) async {
  await tester.pumpWidget(MaterialApp(home: Text('Hello')));
  expect(find.text('Hello'), findsOneWidget);
});