NvGolden

init()

The init method must be called in the setUpAll callback to load the fonts. Otherwise your screenshots will contain black squares instead of readable text.

device()

The NvGolden.device(...) constructor takes a list of Screen Objects. You can create your own or use the ones provided in Device.

grid()

The NvGolden.grid(...) constructor takes a nrColumns argument specifying the number of columns for your golden file. You can pass in one global Screen Object or have each Scenario with it's own Screen.

addScenario()

The addScenario(...) method is the place where all the magic happens. Pass in a name and the widget you want to test and you are good to go.

TL;DR

The following test shows you pretty much everything there is to know.

  setUpAll(loadAppFonts);

  testWidgets('test widget with universal screen size in 2x2 grid',
      (tester) async {
    final smallDevice = Screen(size: Size(150, 60));

    final nvGolden = NvGolden.grid(nrColumns: 2, screen: smallDevice)
      ..addScenario(
        name: 'Title',
        widget: nvWrapper.wrap(
          SampleIconButton(
            text: 'Title',
            icon: Icons.title,
          ),
        ),
      )
      ..addScenario(
        name: 'Circle',
        widget: nvWrapper.wrap(
          SampleIconButton(
            text: 'Circle',
            icon: Icons.circle,
          ),
        ),
      );

    await tester.createGolden(nvGolden, 'icon_button_universal_size');
  });
}

It produces the following screenshot/golden:

Google Fonts

To user this plugin with google_fonts you'll need to first download the font (as recommended by google_fonts) and then use the NvGolden.loadFonts(...) method with the correct font name as well as paths to your font files.