car-interface-android/test/obd_economy_test.dart

import 'package:cardash_launcher/features/home/obd_economy.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  test('MAF and speed produce a rolling L/100 km value', () {
    final economy = ObdEconomy();
    final start = DateTime(2026, 10, 29, 12);
    for (var i = 0; i <= 40; i++) {
      economy.add(
        at: start.add(Duration(seconds: i)),
        speedKmh: 60,
        mafGps: 12,
        throttlePercent: 20,
      );
    }
    expect(economy.accumulatedKm, closeTo(40 * 60 / 3600, 0.12));
    expect(economy.litresPer100Km, closeTo(6.6, 0.2));
  });

  test('idle yields no economy value', () {
    final economy = ObdEconomy();
    final start = DateTime(2026);
    for (var i = 0; i < 10; i++) {
      economy.add(
        at: start.add(Duration(seconds: i)),
        speedKmh: 0,
        mafGps: 4,
        throttlePercent: 2,
      );
    }
    expect(economy.litresPer100Km, isNull);
  });

  test('fuel cut while coasting reads zero consumption', () {
    final economy = ObdEconomy();
    final start = DateTime(2026);
    for (var i = 0; i <= 35; i++) {
      economy.add(
        at: start.add(Duration(seconds: i)),
        speedKmh: 60,
        mafGps: 12,
        throttlePercent: 0,
      );
    }
    expect(economy.litresPer100Km, 0);
  });

  test('reset clears the rolling window', () {
    final economy = ObdEconomy();
    final start = DateTime(2026);
    for (var i = 0; i <= 35; i++) {
      economy.add(
        at: start.add(Duration(seconds: i)),
        speedKmh: 60,
        mafGps: 12,
        throttlePercent: 20,
      );
    }
    expect(economy.litresPer100Km, isNotNull);
    economy.reset();
    expect(economy.litresPer100Km, isNull);
    expect(economy.accumulatedKm, 0);
  });
}