Setting up the project

First of all, you need to create a top-level folder called test; this is where we’re going to spend most of our time. Then, you need to add a new dependency to the pubspec.yaml file since we’re going to use it in the next section. Once you’ve done this, your dev_dependencies should be as follows (if it’s the case, make sure that you update them to their latest versions):

dev_dependencies:
  dart_code_metrics: ^4.8.1
  flutter_lints: ^1.0.4
  flutter_test:
    sdk: flutter
  golden_toolkit: ^0.12.0

Finally, we need to create a useful widget that wraps a common configuration that’s required by all the widgets we’re going to test. Since the app is based on a material design, our class is going to wrap a MaterialApp and a Scaffold widget. Place this widget inside the test folder and name it whatever you want; for example, mock_wrapper.dart:

class MockWrapper...