在此代码中找不到只是重构代码的错误 [已关闭]

问：

我有一段 C# 代码，我打算重构并使其变得更好 - 遵守 SOLID、DRY、KISS 等标准。原始代码为：

public class CustomerService
    {
        public bool AddCustomer(string firname, string surname, string email, DateTime dateOfBirth, int companyId)
        {
            if (string.IsNullOrEmpty(firname) || string.IsNullOrEmpty(surname))
            {
                return false;
            }

            if (!email.Contains("@") && !email.Contains("."))
            {
                return false;
            }

            var now = DateTime.Now;
            int age = now.Year - dateOfBirth.Year;
            if (now.Month < dateOfBirth.Month || (now.Month == dateOfBirth.Month && now.Day < dateOfBirth.Day)) age--;

            if (age < 21)
            {
                return false;
            }

            var companyRepository = new CompanyRepository();
            var company = companyRepository.GetById(companyId);

            var customer = new Customer
                               {
                                   Company = company,
                                   DateOfBirth = dateOfBirth,
                                   EmailAddress = email,
                                   Firstname = firname,
                                   Surname = surname
                               };

            if (company.Name == "VeryImportantClient")
            {
                // Skip credit check
                customer.HasCreditLimit = false;
            }
            else if (company.Name == "ImportantClient")
            {
                // Do credit check and double credit limit
                customer.HasCreditLimit = true;
                using (var customerCreditService = new CustomerCreditServiceClient())
                {
                    var creditLimit = customerCreditService.GetCreditLimit(customer.Firstname, customer.Surname, customer.DateOfBirth).Result;
                    creditLimit = creditLimit*2;
                    customer.CreditLimit = creditLimit;
                }
            }
            else
            {
                // Do credit check
                customer.HasCreditLimit = true;
                using (var customerCreditService = new CustomerCreditServiceClient())
                {
                    var creditLimit = customerCreditService.GetCreditLimit(customer.Firstname, customer.Surname, customer.DateOfBirth).Result;
                    customer.CreditLimit = creditLimit;
                }
            }

            if (customer.HasCreditLimit && customer.CreditLimit < 500)
            {
                return false;
            }

            CustomerDataAccess.AddCustomer(customer);

            return true;
        }
    }
}

我将其重构如下：

    public bool AddCustomer(string firname, string surname, string email, DateTime dateOfBirth, int companyId)
    {
        if (!_customerValidator.ValidateCustomer(firname, surname, email, dateOfBirth))
        {
            return false;
        }

        var company = _companyRepository.GetById(companyId);
        var customer = _customerFactory.CreateCustomer(firname, surname, email, dateOfBirth, company);

        customer.HasCreditLimit = _creditLimitCalculator.AssessCreditLimit(company.Name);
        customer.CreditLimit = _creditLimitCalculator.RetrieveCreditLimit(customer);

        if (!_creditLimitValidator.HasCreditLimit(customer))
        {
            return false;
        }

        _customerDataAccessFactory.AddCustomer(customer);

        return true;
    }
}

我基本上希望类只调用方法以尽可能多地满足 SOLID 和 DRY。

当我提交此代码时，它是根据一系列未提供给我们的测试来判断的，我被告知的错误是：

There was a mistake that made the credit check work in reverse, which broke business logic. 

处理它的新代码的相关部分只是从原始代码中剥离出来，基本上在这里：

public class CreditLimitCalculator : ICreditLimitCalculator
{
    public bool AssessCreditLimit(string companyName)
    {
        if (companyName == Company.VeryImportantClient)
        {
            return true;
        }
        return false;
    }

    public int RetrieveCreditLimit(Customer customer)
    {
        int creditLimit;
        switch (customer.Company.Name)
        {
            case Company.VeryImportantClient:
                creditLimit = customer.CreditLimit;
                break;

            case Company.ImportantClient:
                using (var customerCreditService = new CustomerCreditServiceClient())
                {
                    var limit = customerCreditService.GetCreditLimit(customer.Firstname, customer.Surname, customer.DateOfBirth).Result;
                    limit *= 2;
                    creditLimit = limit;
                }

                break;

            default:
                using (var customerCreditService = new CustomerCreditServiceClient())
                {
                    var limit = customerCreditService.GetCreditLimit(customer.Firstname, customer.Surname, customer.DateOfBirth).Result;
                    creditLimit = limit;
                }
                break;
        }

        return creditLimit;
    }
}

和：

public bool HasCreditLimit(Customer customer)
{
    if (customer.HasCreditLimit && customer.CreditLimit < 500)
    {
        return false;
    }

    return true;
}

它基本上是完全相同的代码，只是移动到不同的类中，所以我不知道为什么它失败了。它也无法初始化，因此也无法调试和单步执行它。有什么建议吗？