How can I change the font during golden tests?

[robkri]

I would like to use golden tests for some UI testing. As fonts tend to get rendered slightly differently on different OS Flutter apparently automatically uses the font "Ahem" when running test. Should a FluentApp show that behaviour during tests, too? If not, is there an easy way to achieve that?

I'm using theme extensions to manage typography etc. in my fluent application and during tests the fonts are used that I defined. This causes golden tests to fail between different OS.

[robkri]

I found a solution:

Add font as asset and change pubspec.yaml:

fonts:
    - family: Ahem
      fonts:
        - asset: assets/fonts/ahem.ttf

In your test:

  bool isTestRunning;

  Future<void> setUpAll() async {
    isTestRunning = true;

    // Explicitly load the font.
    final fontData = await rootBundle.load("assets/fonts/ahem.ttf");
    final fontLoader = FontLoader("Ahem");
    fontLoader.addFont(Future.value(fontData));
    await fontLoader.load();
  }

Wherever the font is set in the application do something like:

  font = isTestRunning ? TextStyle(fontFamily: "Ahem") : myRegularFont;

[robkri]

Let me know if there's a better way to do this.