CS0266 - 无法将类型 "System IList" 隐式转换为 "System ArrayList" - 软件测试

Question

我正在尝试为我的软件测试任务创建几个模拟单元测试，但我的 GUI.cs 文件有一个错误，表明它无法将类型 "System.Collections.IList" 隐式转换为 "System.Collection.ArrayList"

this.accounts = database.GetAccounts();

但是该文件未被修改。我的意思是我没有修改它。我修改的唯一文件是单元测试、文件数据库和 Idatabase，如下所列，通过更改一些变量类型，例如将我的所有 ArrayList 重命名为 IList。

但是我的 GUI 有错误，我无法确定是哪个文件和哪一行代码引起的。

下面是 GUI.cs 文件

错误是 "this.accounts..." 行。

当我将鼠标悬停在 Visual Studio 上时，两条 "dataGridView1" 行出现一些 System.NullReferenceException 错误。这可能与我遇到的错误有关，我不太确定。

private void InitBankRead()
        {
            try
            {
                //database = new FileDatabase();
                database = IoC.GetInstance().Resolve<IDatabase>();

                this.accounts = database.GetAccounts();
                this.dataGridView1.DataSource = accounts;

                dataGridView1.Columns["Balance"].DefaultCellStyle.Format = "C";

                foreach (DataGridViewColumn column in dataGridView1.Columns)
                {
                    dataGridView1.Columns[column.Name].SortMode = DataGridViewColumnSortMode.Automatic;
                }
            }

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编辑：

下面是我的其余文件，供任何想深入研究的人使用。它是可选的，但它在那里。我的目的不是要用我的作品压倒你们，而是要确保你们明白我在说什么。

IDatabase.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections;
using Banking;


namespace Banking
{
    public interface IDatabase
    {
        //IList<Account> FindAll();
        //Account FindByAccount(int accountId);
        //Account FindByName(int firstName, int lastName);
        //bool Save(Account target);

        bool AddNewCustomer(int customerId, string firstName, string lastName, decimal openingDeposit, Account.ACCOUNTTYPE type);
        bool UpdateExistingAccount(char transactionType, Account account, decimal amount);
        IList GetAccounts();

    }
}

FileDatabase.cs

using System;
using System.Collections;
using System.IO;
using Banking;

namespace Banking
{
    public class FileDatabase : IDatabase
    {
        private string filename;
        private StreamWriter outFile;
        private StreamReader inFile;
        public const string DELIMETER = ",";

        public FileDatabase()
        {
            this.filename = @"..\..\..\Banking\Data\Database.txt";
        }

        public bool AddNewCustomer(int customerID, string firstName, string lastName, decimal openingDeposit, Account.ACCOUNTTYPE type)
        {
            int accountID = GetAccounts().Count + 1;
            using (outFile = File.AppendText(filename))
            {
                string output = accountID + DELIMETER + customerID + DELIMETER + firstName + DELIMETER + lastName + DELIMETER + openingDeposit + DELIMETER + Convert.ToInt32(type);
                outFile.WriteLine(output);

                outFile.Close();
            }
            return true;
        }
        public bool UpdateExistingAccount(char transactionType, Account account, decimal amount)
        {
            bool success = false;
            try
            {
                switch (transactionType)
                {
                    case 'D':
                        //account.Balance += amount;
                        account.deposit(amount);
                        break;
                    case 'W':
                        //account.Balance -= amount;
                        account.withdrawl(amount);
                        break;
                }

                IList accounts = GetAccounts();
                int accountID = account.AccountID;

                // Find and replace the account
                for (int i = 0; i < accounts.Count; ++i)
                {
                    if (accountID == ((Account) accounts[i]).AccountID)
                    {
                        accounts[i] = account;
                    }
                }

                using (outFile = new StreamWriter(filename))
                {
                    foreach (Account acct in accounts)
                    {
                        outFile.WriteLine(acct.AccountID + DELIMETER + acct.Customer.CustomerID + DELIMETER + acct.Customer.FirstName + DELIMETER + acct.Customer.LastName + DELIMETER + acct.Balance + DELIMETER + Convert.ToInt32(acct.AccountType));
                    }
                    outFile.Close();
                }
                success = true;
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
                success = false;
            }
            return success;
        }

        public IList GetAccounts()
        {
            IList accounts = new ArrayList();

            using (inFile = new StreamReader(filename))
            {
                int customerID;
                int accountID;
                string firstName;
                string lastName;
                decimal balance;
                int accountType;
                string line = string.Empty;

                while ((line = inFile.ReadLine()) != null)
                {
                    string [] data = line.Split(DELIMETER.ToCharArray()[0]);

                    customerID = Convert.ToInt32(data[0]);
                    accountID = Convert.ToInt32(data[1]);
                    firstName = Convert.ToString(data[2]);
                    lastName = Convert.ToString(data[3]);
                    balance = Convert.ToDecimal(data[4]);
                    accountType = Convert.ToInt32(data[5]);

                    Customer customer = new Customer(customerID, firstName, lastName);
                    Account account;

                    Account.ACCOUNTTYPE type = (Account.ACCOUNTTYPE) accountType;
                    if (type == Account.ACCOUNTTYPE.CHECKING)
                    {
                        account = new Checking(customer, accountID, Convert.ToDecimal(balance));
                    }
                    else
                    {
                        account = new Savings(customer, accountID, Convert.ToDecimal(balance));
                    }

                    accounts.Add(account);
                }
                inFile.Close();
            }
            return accounts;
        }
    }
}

UnitTest.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Banking;
using Moq;


namespace UnitTestsWithMoQ
{
    [TestClass]
    public partial class UnitTest1
    {
        public TestContext TestContext { get; set; }
        public readonly IDatabase MockDatabase;

        private IList accounts = new List<Account>
        {
            new Checking( new Customer(1, "Alex", "Parrish"), 12, 30.00M ),
            new Savings( new Customer(2, "Alex", "Russo"), 12, 29.00M ),
            new Checking( new Customer(3, "Emma", "Swan"), 12, 30.00M ),
            new Savings( new Customer(4, "Henry", "Mills"), 12, 30.00M )
        };
        Mock<IDatabase> dataMock = new Mock<IDatabase>();


        private string filename;
        private StreamWriter outFile;
        private StreamReader inFile;
        public const string DELIMETER = ",";

        public UnitTest1()
        {
            // Return all accounts
            dataMock.Setup(repository => repository.GetAccounts()).Returns(accounts);
            dataMock.Setup(repository => repository.UpdateExistingAccount(It.IsAny<char>(), It.IsAny<Account>(),
                It.IsAny<decimal>())).Returns((char transactionType, Account account, decimal amountDecimal) =>
            {
                bool success = false;
                try
                {
                    switch (transactionType)
                    {
                        case 'D':
                            //account.Balance += amount;
                            account.deposit(amountDecimal);
                            break;
                        case 'W':
                            //account.Balance -= amount;
                            account.withdrawl(amountDecimal);
                            break;
                    }

                    var accounts = MockDatabase.GetAccounts();
                    int accountID = account.AccountID;

                    // Find and replace the account
                    for (int i = 0; i < accounts.Count; ++i)
                    {
                        if (accountID == ((Account) accounts[i]).AccountID)
                        {
                            accounts[i] = account;
                        }
                    }
                    // Find and replace the account
                    for (int i = 0; i < accounts.Count; ++i)
                    {
                        MockDatabase.GetAccounts()[i] = accounts[i];
                    }

                }

                catch (Exception e)
                {
                    Console.WriteLine(e.ToString());
                    success = false;

                }

                return success;

            });

            dataMock.Setup(repository => repository.AddNewCustomer(It.IsAny<int>(), It.IsAny<string>(), It.IsAny<string>(), It.IsAny<decimal>(),
                It.IsAny<Account.ACCOUNTTYPE>())).Returns((int customerID, string firstName, string lastName, decimal openingDeposit, Account.ACCOUNTTYPE type) =>
            {
                int accountID = MockDatabase.GetAccounts().Count + 1;
                using (outFile = File.AppendText(filename))
                {
                    string output = accountID + DELIMETER + customerID + DELIMETER + firstName + DELIMETER + lastName + DELIMETER + openingDeposit + DELIMETER + Convert.ToInt32(type);
                    outFile.WriteLine(output);

                    outFile.Close();
                }
                return true;

            });


            MockDatabase = dataMock.Object;
        }

    }
}

Answer 1

如果错误显示 cannot implicitly convert type "System.Collections.IList" to "System.Collection.ArrayList"，那么您可能正在将 IList 变量分配给 ArrayList 变量。

注意 IList 是一个比具体类型 ArrayList 更通用的接口，所以编译器不知道如何隐式转换它。

this.accounts = database.GetAccounts();

accounts 是如何定义的？

如果定义为：ArrayList accounts 那么您将无法进行该作业。

尝试将其更改为：IList accounts

CS0266 - 无法将类型 "System IList" 隐式转换为 "System ArrayList" - 软件测试

CS0266 - Cannot implicitly convert type "System IList" to "System ArrayList" - Software Testing

c#

testing

moq

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