找不到 Autofixture 循环引用

Question

我正在使用 Autofixture 生成我的测试模型，但在一种情况下它说我的模型有一个我找不到的循环引用。失败的模型是 RepresentationExpense 类，我唯一​​能想到的是它与继承有关，因为 Expense 类没有同样的问题：

public class RepresentationExpense : Expense
{
    public string GuestName { get; private set; }
    public string GuestCompany { get; private set; }

    public RepresentationExpense(ExpenseId id, ExpenseReportId reportId, EmployeeId employeeId, string description, Payment payment, DateTime created, PaymentMethod paymentMethod, ReceiptId receiptId, string guestName, string guestCompany, string comment = null)
        : base(id, reportId, employeeId, description, payment, created, paymentMethod, CategoryType.Representation, receiptId, comment)
    {
        Verify.ArgumentNotNull(guestName, "guestName");
        Verify.ArgumentNotNull(guestCompany, "guestCompany");

        GuestName = guestName;
        GuestCompany = guestCompany;
    }
}

public class Expense
{
    public ExpenseId Id { get; private set; } // simple wrapper for long
    public ExpenseReportId ReportId { get; private set; } // simple wrapper for long
    public EmployeeId EmployeeId { get; private set; } // simple wrapper for long
    public Payment Payment { get; private set; }
    public DateTime Created { get; private set; }
    public PaymentMethod PaymentMethod { get; private set; } // enum
    public CategoryType CategoryType { get; private set; } // enum
    public ReceiptId ReceiptId { get; private set; } // simple wrapper for long
    public string Description { get; private set; }
    public string Comment { get; private set; }

    public Expense(ExpenseId id, ExpenseReportId reportId, EmployeeId employeeId, string description, Payment payment, DateTime created, PaymentMethod paymentMethod, CategoryType categoryType, ReceiptId receiptId, string comment = null)
    {
        Verify.ArgumentNotDefault(id, "id");
        Verify.ArgumentNotDefault(reportId, "reportId");
        Verify.ArgumentNotDefault(employeeId, "employeeId");
        Verify.ArgumentNotDefault(created, "created");
        Verify.ArgumentNotNull(categoryType, "category");
        Verify.ArgumentNotNull(payment, "payment");
        Verify.ArgumentNotNull(paymentMethod, "paymentMethod");
        Verify.ArgumentNotDefault(receiptId, "receipt");
        Verify.ArgumentNotNull(description, "description");
        Verify.Argument(receiptId != ReceiptId.Unassigned, "Must have an existing report");
        Verify.Argument(reportId != ExpenseReportId.Unassigned, "Must have an existing report");

        Id = id;
        ReportId = reportId;
        EmployeeId = employeeId;
        Created = created;
        CategoryType = categoryType;
        Payment = payment;
        PaymentMethod = paymentMethod;
        ReceiptId = receiptId;
        Description = description;
        Comment = comment;
    }
}

public sealed class Payment
{
    public Money Money { get; private set; } // simple class
    public ExchangeRate ExchangeRate { get; private set; } // simple class
    public DateTime Date { get; private set; }

    public Payment(Money money, ExchangeRate exchangeRate, DateTime date)
    {
        Verify.ArgumentNotNull(money, "money");
        Verify.ArgumentNotNull(exchangeRate, "exchangeRate");
        Verify.ArgumentNotDefault(date, "date");
        Verify.Argument(money.Currency.Name == exchangeRate.Currency.Name, "Currency must be the same for money and exchange rate");
        Verify.Operation(date <= DateTime.Now, "You cannot create a payment in the future");

        Money = money;
        ExchangeRate = exchangeRate;
        Date = date;
    }
}

这是错误消息。不过，我并没有完全遵循上述路径。

Ploeh.AutoFixture.Idioms.GuardClauseException : AutoFixture was unable to create an instance for parameter "payment" of method ".ctor".
Method Signature: Void .ctor(BLL.Modules.Expenses.Models.ExpenseId, BLL.Modules.Expenses.Models.ExpenseReportId, BLL.Modules.Expenses.Models.EmployeeId, System.String, BLL.Modules.Expenses.Models.Payment, System.DateTime, BLL.Modules.Expenses.Models.PaymentMethod, BLL.Modules.Expenses.Models.ReceiptId, System.String, System.String, System.String)
Declaring Type: BLL.Modules.Expenses.Models.RepresentationExpense
Reflected Type: BLL.Modules.Expenses.Models.RepresentationExpense
  ----> Ploeh.AutoFixture.ObjectCreationException : AutoFixture was unable to create an instance of type System.RuntimeType because the traversed object graph contains a circular reference. Information about the circular path follows below. This is the correct behavior when a Fixture is equipped with a ThrowingRecursionBehavior, which is the default. This ensures that you are being made aware of circular references in your code. Your first reaction should be to redesign your API in order to get rid of all circular references. However, if this is not possible (most likely because parts or all of the API is delivered by a third party), you can replace this default behavior with a different behavior: on the Fixture instance, remove the ThrowingRecursionBehavior from Fixture.Behaviors, and instead add an instance of OmitOnRecursionBehavior.
    Path:
        BLL.Modules.Expenses.Models.Payment --> 
        BLL.Modules.Expenses.Models.Payment payment --> 
        BLL.Modules.Expenses.Models.Payment
Result StackTrace:  
at Ploeh.AutoFixture.Idioms.GuardClauseAssertion.GetParameters(IMethod method)
at Ploeh.AutoFixture.Idioms.GuardClauseAssertion.GetParameterGuardCommands(IMethod method)
at Ploeh.AutoFixture.Idioms.GuardClauseAssertion.VerifyNormal(IMethod method)
at Ploeh.AutoFixture.Idioms.GuardClauseAssertion.Verify(IMethod method, Boolean isReturnValueIterator)
at Ploeh.AutoFixture.Idioms.GuardClauseAssertion.Verify(ConstructorInfo constructorInfo)
at Ploeh.AutoFixture.Idioms.IdiomaticAssertion.Verify(ConstructorInfo[] constructorInfos)
at Ploeh.AutoFixture.Idioms.IdiomaticAssertion.Verify(Type type)
at WorkxoneUnitTests.TestBase`1.AssertGuardClausesForType() in c:\Code\Comenxa\WorkxoneUnitTests\TestBase.cs:line 58
at WorkxoneUnitTests.BLL.Modules.Expenses.Models.RepresentationExpenseTests.Guards_are_asserted() in c:\Code\Comenxa\WorkxoneUnitTests\BLL\Modules\Expenses\Models\RepresentationExpenseTests.cs:line 24
--ObjectCreationException
at Ploeh.AutoFixture.Kernel.ThrowingRecursionHandler.HandleRecursiveRequest(Object request, IEnumerable`1 recordedRequests)
at Ploeh.AutoFixture.Kernel.RecursionGuard.HandleRecursiveRequest(Object request)
at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
at Ploeh.AutoFixture.Fixture.Create(Object request, ISpecimenContext context)
at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request)
at Ploeh.AutoFixture.Idioms.SpecimenBuilderComposer.CreateAnonymous(ISpecimenBuilder builder, Object request)
at Ploeh.AutoFixture.Idioms.GuardClauseAssertion.GetParameters(IMethod method)

Answer 1

我通过将夹具配置为忽略循环引用解决了这个问题

var fixture = new Fixture();
fixture.Behaviors.Remove(new ThrowingRecursionBehavior());
fixture.Behaviors.Add(new OmitOnRecursionBehavior());

source

Answer 2

当构造函数中抛出异常时，我设法重现。您可以调试代码并检查哪个对象未通过“验证部分”。然后您可以尝试freeze 将在测试中使用的有效对象。或者您可以使用 ISpecimenBuilder 自定义 autofixture