使用moq设置一个方法来返回一个对象列表，但结果为null

本文关键字：列表 一个对象 返回 null 结果 方法 设置 moq 一个 使用 | 更新日期: 2023-09-27 17:57:37

我一直在个人项目中进行测试，遇到了这个小问题。我有一个创建对象列表的测试方法，我设置了一个在方法中使用的服务，我测试该服务以返回模拟列表。无论如何，由于某种原因，设置不起作用，并且返回null。

以下是测试方法：

var mockList = new List<IBillItem>
{
    new BillItem
    {
        Id = 0,
        DueDate = new DateTime(),
        Name = "",
        IndexNumber = "",
        AccountNumber = "",
        Amount = decimal.One
    },
    new BillItem
    {
        Id = 0,
        DueDate = new DateTime(),
        Name = "",
        IndexNumber = "",
        AccountNumber = "",
        Amount = decimal.One
    }
};
_billHandlingService.Setup(x => x.GetAllBillsAsync(It.IsAny<string>())).Returns(Task.FromResult(mockList));
var listBillsVm = new ListBillsViewModel(new LoggerFactory(), _billHandlingService.Object, _settingsService.Object);
await listBillsVm.GetBillsAsync();
_billHandlingService.Verify(x => x.GetAllBillsAsync(_settingsService.Name), Times.AtMostOnce);
Assert.AreEqual(1, listBillsVm.BillsList.Count);

这是混凝土类im测试的代码：

public async Task GetBillsAsync()
{
    BillsList.Clear();
    var bills = await _billHandlingService.GetAllBillsAsync(_settingsService.LoggerUser);
    if (null != bills)
    {
        var billsByDate = bills.Where(x => x.DueDate == DateTime.Today).ToList();
        foreach (var bill in billsByDate)
        {
            BillsList.Add(bill);
            RaisePropertyChanged(nameof(BillsList));
        }
    }
}

我试过在SO/谷歌上搜索结果，但没有找到任何答案。提前谢谢。

编辑：代码没有评论，但我相信它足够清楚，请在评论中询问是否有什么需要清除

编辑2:

Task<List<IBillItem>>GetAllBillsAsync(string username);

是被调用方法的接口。

使用moq设置一个方法来返回一个对象列表，但结果为null

您可以尝试将Setup中的.Returns更改为.ReturnsAsync(mockList)

//...other code removed for brevity
_billHandlingService
    .Setup(x => x.GetAllBillsAsync(It.IsAny<string>()))
    .ReturnsAsync(mockList);
//...other code removed for brevity

更新

根据你的问题，使用了以下最小的完全可验证的例子来尝试重现你的问题。请注意，我省略了创建测试所不需要的任何类。

class ListBillsViewModel {
    private IBillHandlingService _billHandlingService;
    private ISettingsService _settingsService;
    public ListBillsViewModel(IBillHandlingService billHandlingService, ISettingsService settingsService) {
        this._billHandlingService = billHandlingService;
        this._settingsService = settingsService;
        BillsList = new List<IBillItem>();
    }
    public List<IBillItem> BillsList { get; set; }
    public async Task GetBillsAsync() {
        BillsList.Clear();
        var bills = await _billHandlingService.GetAllBillsAsync(_settingsService.LoggerUserName);
        if (null != bills) {
            var billsByDate = bills.Where(x => x.DueDate == DateTime.Today).ToList();
            foreach (var bill in billsByDate) {
                BillsList.Add(bill);
            }
        }
    }
}
public interface ISettingsService {
    string Name { get; }
    string LoggerUserName { get; set; }
}
public interface IBillHandlingService {
    Task<List<IBillItem>> GetAllBillsAsync(string username);
}
public class BillItem : IBillItem {
    public int Id { get; set; }
    public DateTime DueDate { get; set; }
    public string Name { get; set; }
    public string IndexNumber { get; set; }
    public string AccountNumber { get; set; }
    public decimal Amount { get; set; }
}
public interface IBillItem {
    int Id { get; set; }
    DateTime DueDate { get; set; }
    string Name { get; set; }
    string IndexNumber { get; set; }
    string AccountNumber { get; set; }
    decimal Amount { get; set; }
}

然后，基于上述类重构以下单元测试

[TestMethod]
public async Task Moq_Setup_Should_Return_List_Of_Objects() {
    var mockList = new List<IBillItem>
    {
        new BillItem
        {
            Id = 0,
            DueDate = DateTime.Today,
            Name = "User",
            IndexNumber = "",
            AccountNumber = "",
            Amount = decimal.One
        },
        new BillItem
        {
            Id = 1,
            DueDate = DateTime.Today.AddDays(1),
            Name = "User",
            IndexNumber = "",
            AccountNumber = "",
            Amount = decimal.One
        }
    };
    string name = "User";
    var _settingsService = new Mock<ISettingsService>();
    _settingsService
        .Setup(m => m.Name)
        .Returns(name);
    _settingsService
        .Setup(m => m.LoggerUserName)
        .Returns(name);
    var _billHandlingService = new Mock<IBillHandlingService>();
    _billHandlingService
        .Setup(x => x.GetAllBillsAsync(It.IsAny<string>()))
        .ReturnsAsync(mockList);
    var listBillsVm = new ListBillsViewModel(_billHandlingService.Object, _settingsService.Object);
    await listBillsVm.GetBillsAsync();
    _billHandlingService.Verify(x => x.GetAllBillsAsync(_settingsService.Name), Times.AtMostOnce);
    Assert.AreEqual(1, listBillsVm.BillsList.Count);
}

我运行了上面的测试，它通过了.Returns(Task.FromResult(mockist))和.ReturnsAsync(mockList)这两个设置的预期。

要么你给出的例子与你的实际情况不符，要么问题超出了你在帖子中描述的范围。

您需要在Task.FromResult上指定List<IBillItem>，如下所示：

_billHandlingService.Setup<Task<List<IBillItem>>>(
    x => x.GetAllBillsAsync(It.IsAny<string>()))
                    .Returns(Task.FromResult<List<IBillItem>>(mockList));

此处类似SO Q和A。

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