public void DecreaseStockCount_By_One_Stock_Is_Not_Empty()
{
// Arrange
Drug drug = new Drug("Ibuprophen");
Fakes.FakeStockProvider stockProvider = new Fakes.FakeStockProvider(10);
Stock stock = new Stock(stockProvider);
Assert.That(stock.StockCount(drug), Is.EqualTo(10));
// Act
stock.DecreaseStock(drug, 1);
// Assert
Assert.That(stock.StockCount(drug), Is.EqualTo(9));
}