public static assert I_should_have_150_shares_of_APPL_stock(this assert fixtures) => fixtures.Expect(x => x.Stocks.Shares["APPL"].Should().Be(150));
public static assert A_sell_order_for_20_shares_of_MSFT_stock_should_have_been_executed(this assert fixtures) => fixtures.Expect(x => x.Stocks.Orders["MSFT"].Should().Be(20));
public static assert I_should_have_80_shares_of_MSFT_stock(this assert fixtures) => fixtures.Expect(x => x.Stocks.Shares["MSFT"].Should().Be(80));