创建的IEqualityComparer<&IEnumerable的LT; T>> [英] Creating a IEqualityComparer<IEnumerable<T>>

问题描述

我使用的xUnit，它并没有办法来确定是否2 的IEnumerable< T> 都是平等的，如果 T 是自定义类型。

I'm using xUnit and it doesn't have a way to determine if 2 IEnumerable<T> are equal if T is custom type.

我试过使用 LINQ SequenceEqual 但同样作为实例 T 是不同的这一返回false;

I've tried using LINQ SequenceEqual but again as the instances of T are different this returns false;

下面是一个基本的测试非工作的IEqualityComparer

Here is a basic test with a non-working IEqualityComparer

    [Fact]
    public void FactMethodName()
    {
        var one = new[] { new KeywordSchedule() { Id = 1 } };
        var two = new[] { new KeywordSchedule() { Id = 1 } };

        Assert.Equal(one, two, new KeywordScheduleComparer());
    }

public class KeywordScheduleComparer : IEqualityComparer<IEnumerable<KeywordSchedule>>
{
    public bool Equals(IEnumerable<KeywordSchedule> x, IEnumerable<KeywordSchedule> y)
    {
        return Object.ReferenceEquals(x, y) || (x != null && y != null && x.SequenceEqual(y));
    }

    public int GetHashCode(IEnumerable<KeywordSchedule> obj)
    {
        if (obj == null)
            return 0;

        return unchecked(obj.Select(e => e.GetHashCode()).Aggregate(0, (a, b) => a + b));  // BAD
    }
}

我在集成使用此测试，所以我在一开始插入从IEnumerable数据转换成一个数据块，然后叫我SUT从数据库检索数据并进行比较。

I'm using this in an integration test, so I insert data from a IEnumerable into a DB at the start, then call my SUT to retrieve data from DB and compare.

如果你能帮助我得到一个！收集比较工作，我会很感激的。

If you can help me get a collection comparison working I'd appreciate it!

推荐答案

我只是验证了该工作正常xUnit.net 1.9.2：

I just verified that this works fine with xUnit.net 1.9.2:

public class MyClass
{
    public int ID { get; set; }
    public string Name { get; set; }
}

public class MyClassComparer : IEqualityComparer<MyClass>
{
    public bool Equals(MyClass x, MyClass y)
    {
        return x.ID == y.ID;
    }

    public int GetHashCode(MyClass obj)
    {
        return obj.ID.GetHashCode();
    }
}

public class ExampleTest
{
    [Fact]
    public void TestForEquality()
    {
        var obj1 = new MyClass { ID = 42, Name = "Brad" };
        var obj2 = new MyClass { ID = 42, Name = "Joe" };

        Assert.Equal(new[] { obj1 }, new[] { obj2 }, new MyClassComparer());
    }
}

所以，我不是100％清楚为什么你需要额外的比较器。只是单一的比较器就足够了。

So I'm not 100% clear why you need the extra comparer. Just the single comparer should be sufficient.

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