halkyon/halkyon_learn_flutter/test/feature/jellyfin/ambient_glow_test.dart

import 'dart:async';
import 'dart:typed_data';
import 'dart:ui' as ui;

import 'package:flutter_test/flutter_test.dart';
import 'package:halkyon_learn_flutter/src/feature/jellyfin/widget/ambient_glow.dart';
import 'package:material_ui/material_ui.dart';

/// An image one pixel high, of [colors] in turn.
Future<ui.Image> pixels(List<Color> colors) {
  final bytes = Uint8List.fromList([
    for (final color in colors) ...[
      (color.r * 255).round(),
      (color.g * 255).round(),
      (color.b * 255).round(),
      (color.a * 255).round(),
    ],
  ]);
  final done = Completer<ui.Image>();
  ui.decodeImageFromPixels(
    bytes,
    colors.length,
    1,
    ui.PixelFormat.rgba8888,
    done.complete,
  );
  return done.future;
}

void main() {
  testWidgets("a picture's colour is its pixels' average, the clear ones "
      'left out', (tester) async {
    final colour = await tester.runAsync(() async {
      final image = await pixels(const [
        Color(0xFFFF0000),
        Color(0xFF0000FF),
        Color(0x00FFFFFF),
      ]);
      try {
        return await averageColourOf(image);
      } finally {
        image.dispose();
      }
    });

    expect(colour, const Color(0xFF7F007F));
  });

  test('the panel takes the colour no lighter than text stays readable '
      'on, keeping its hue', () {
    final snow = panelColourOf(const Color(0xFFF4F8FF));
    final night = panelColourOf(const Color(0xFF101830));

    expect(HSLColor.fromColor(snow).lightness, closeTo(0.35, 0.01));
    expect(
      HSLColor.fromColor(snow).hue,
      closeTo(HSLColor.fromColor(const Color(0xFFF4F8FF)).hue, 1),
    );
    // Dark enough already: as it is.
    expect(night, const Color(0xFF101830));
  });
}