public void TestPrice()
{
_repository = Substitute.For <IInstrumentRepository>();
_repository.GetInstruments()
.Returns(new List <Instrument>
{
new Instrument("Toto", InstrumentType.Bond)
});
_pricer = new Pricer(_repository, 500);
_pricer.Price();
Thread.Sleep(800);
_repository.Received(1).PriceUpdate("Toto", Arg.Any <double>());
}