public void Check_WhenTemperatureIsLowerAndHeaterIsNotStarted_ShouldStartHeater() { _currentTemperatureProvider.Stub(x => x.GetTemperature()).Return(19); _temperatureSettingsProvider.Stub(x => x.GetRequestedTemperature()).Return(20); _thermostat.Check(); _heater.AssertWasCalled(x => x.Start()); }