c# – 联合两个自定义类返回重复项

我有两个自定义类,ChangeRequest和ChangeRequests,其中ChangeRequests可以包含许多ChangeRequest实例.

public class ChangeRequests : IXmlSerializable, ICloneable, IEnumerable<ChangeRequest>,
    IEquatable<ChangeRequests> { ... }

public class ChangeRequest : ICloneable, IXmlSerializable, IEquatable<ChangeRequest>
    { ... }

我试图做两个ChangeRequests实例的联合.但是,似乎没有删除重复项.我的MSTest单元测试如下：

var cr1 = new ChangeRequest { CRID = "12" };
var crs1 = new ChangeRequests { cr1 };
var crs2 = new ChangeRequests
               {
                   cr1.Clone(),
                   new ChangeRequest { CRID = "34" }
               };
Assert.AreEqual(crs1[0], crs2[0], "First CR in both ChangeRequests should be equal");
var unionedCRs = new ChangeRequests(crs1.Union<ChangeRequest>(crs2));
ChangeRequests expected = crs2.Clone();
Assert.AreEqual(expected, unionedCRs, "Duplicates should be removed from a Union");

测试在最后一行失败,unionedCRs包含两个cr1副本.当我尝试调试并逐步执行每一行时,我在第一行的ChangeRequest.Equals(object)中以及ChangeRequest.Equals(ChangeRequest)的第一行中有一个断点,但都没有被击中.为什么联合包含重复的ChangeRequest实例？

编辑：根据要求,这里是ChangeRequests.Equals(ChangeRequests)：

public bool Equals(ChangeRequests other)
{
    if (ReferenceEquals(this, other))
    {
        return true;
    }

    return null != other && this.SequenceEqual<ChangeRequest>(other);
}

这里是ChangeRequests.Equals(对象)：

public override bool Equals(object obj)
{
    return Equals(obj as ChangeRequests);
}

编辑：我在ChangeRequest和ChangeRequests上覆盖GetHashCode,但仍然在我的测试中,如果我做IEnumerable< ChangeRequest> unionedCRsIEnum = crs1.Union< ChangeRequest>(crs2);, unionedCRsIEnum以CRID 12的两个ChangeRequest副本结束.

编辑：因为Assert.AreEqual(期望,unionedCRs.Distinct(),“Distinct应该删除重复”),某些地方必须使用我的Equals或GetHashCode实现.失败了,expect和unionedCRs.Distinct()的字符串表示显示unionedCRs.Distinct()肯定有两个CR 12副本.

确保您的GetHashCode实现与您的Equals一致 – Enumerable.Union方法似乎确实使用了两者.

如果你已经实现了一个而不是另一个,你应该从编译器得到警告;你仍然需要确保两种方法相互一致.以下是规则的便捷摘要：Why is it important to override GetHashCode when Equals method is overridden?