如何在保持默认相等检查的同时向 NUnit 添加自定义相等

Question

有没有办法进行自定义约束，先完成 NUnit 的默认相等测试，然后再进行自定义相等测试？

例如，假设我想测试System.Double 的值是否相等，但将Double.PositiveInfinity 视为等于Double.NegativeInfinity。我可以在下面的代码中编写一个简单的测试Comparison 来检查这种特殊情况，然后只使用==。

• 如果我使用Is.EqualTo(expected).Using<double>((x, y) => Comparison(x, y)); 然后NaNisEqualToNaN 失败，因为我没有 NUnit 的默认相等测试。

• 如果我使用Is.EqualTo(expected).Or.EqualTo(expected).Using<double>((x, y) => Comparison(x, y)); 结合自定义测试和默认测试 然后像ShouldFail_NegativeInfinityIsKindaEqualTo7 这样的失败测试会给出重复的错误消息Expected: 7.0d or 7.0d But was...

完整代码示例：

using System;
using NUnit.Framework;
using NUnit.Framework.Constraints;

namespace UnitTest
{
    [TestFixture]
    public class Class1
    {
        private Constraint IsKindaEqualTo(double expected)
        {
            // With this line, ShouldFail_NegativeInfinityIsKindaEqualTo7 reports "Expected: 7.0d or 7.0d But was:  ∞"
            return Is.EqualTo(expected).Or.EqualTo(expected).Using<double>((x, y) => Comparison(x, y));

            // With this line, the NaNisEqualToNaN test fails
            //return Is.EqualTo(expected).Using<double>((x, y) => Comparison(x, y));
        }

        private static bool Comparison(double x, double y)
        {
            if (Double.IsInfinity(x) && Double.IsInfinity(y))
            {
                return true;
            }
            else
            {
                return x == y;
            }
        }

        [Test]
        public void NegativeInfinityIsKindaEqualToPositiveInfinity()
        {
            var actual = Double.NegativeInfinity;
            var expected = Double.PositiveInfinity;

            Assert.That(actual, IsKindaEqualTo(expected));
        }

        [Test]
        public void ShouldFail_NegativeInfinityIsKindaEqualTo7()
        {
            var actual = Double.PositiveInfinity;
            var expected = 7.0;

            Assert.That(actual, IsKindaEqualTo(expected));
        }

        [Test]
        public void NaNisEqualToNaN()
        {
            var actual = Double.NaN;
            var expected = Double.NaN;

            Assert.That(actual, Is.EqualTo(expected));
        }

        [Test]
        public void NaNisKindaEqualToNan()
        {
            var actual = Double.NaN;
            var expected = Double.NaN;

            Assert.That(actual, IsKindaEqualTo(expected));
        }
    }
}

Answer 1

NUnit 的相等比较来自一个名为NUnitEqualityComparer 的类。我将在您的 Comparison 方法中创建并使用其中一个，并将所有内容包装在一个比较器中。例如：

    private static bool Comparison(double x, double y)
    {
        var nunitComparer = new NUnitEqualityComparer();
        if (nunitComparer.AreEqual(x,y)) return true;

        if (Double.IsInfinity(x) && Double.IsInfinity(y))
        {
            return true;
        }
        else
        {
            return x == y;
        }
    }