KeyNotFoundException，但调试时不会出现

Question

我一直在构建一个扩展库，并且使用了在 http://www.extensionmethod 中找到的出色扩展方法。 net 进行包含。在我的单元测试（使用 NUnit 1.5.2）中，我遇到了一个有趣的问题。首先，让我们看一下代码：

    /// <summary>
    /// Groups and aggregates the sequence of elements.
    /// </summary>
    /// <typeparam name="TSource">The source type in the sequence.</typeparam>
    /// <typeparam name="TFirstKey">The first key type to group by.</typeparam>
    /// <typeparam name="TSecondKey">The second key type to rotate by.</typeparam>
    /// <typeparam name="TValue">The type of value that will be aggregated.</typeparam>
    /// <param name="source">The source sequence.</param>
    /// <param name="firstKeySelector">The first key selector.</param>
    /// <param name="secondKeySelector">The second key selector.</param>
    /// <param name="aggregator">The aggregating function.</param>
    /// <returns>A <see cref="Dictionary{TKey,TValue}" /> representing the pivoted data.</returns>    
    public static Dictionary<TFirstKey, Dictionary<TSecondKey, TValue>> Pivot<TSource, TFirstKey, TSecondKey, TValue>
        (this IEnumerable<TSource> source,
         Func<TSource, TFirstKey> firstKeySelector,
         Func<TSource, TSecondKey> secondKeySelector,
         Func<IEnumerable<TSource>, TValue> aggregator)
    {
        return source.GroupBy(firstKeySelector).Select(
            x => new
            {
                X = x.Key,
                Y = x.GroupBy(secondKeySelector).Select(
                    z => new { Z = z.Key, V = aggregator(z) }).ToDictionary(e => e.Z, o => o.V)
            }).ToDictionary(e => e.X, o => o.Y);
    }

该函数的作用是接收类型为 TSource 的 IEnumerable，并将项目转入字典中，并使用您定义的任何函数聚合项目。我的样本数据集是一个人的数组（名为 Person 的类型）。

        private static readonly Person[] people =
        new[]
        {
            new Person { Forename = "Matt", Surname = "Someone", Email = "[email protected]", Age = 25, IsMale = true },
            new Person { Forename = "Chris", Surname = "Someone", Email = "[email protected]", Age = 28, IsMale = false },
            new Person { Forename = "Andy", Surname = "Someone", Email = "[email protected]", Age = 30, IsMale = true },
            new Person { Forename = "Joel", Surname = "Someone", Email = "[email protected]", Age = 30, IsMale = true },
            new Person { Forename = "Paul", Surname = "Someone", Email = "[email protected]", Age = 30, IsMale = true }
        };

最后，我们进行测试：

    /// <summary>
    /// Performs a pivot function on the sample array.
    /// </summary>
    [Test]
    public void Pivot()
    {
        /* Our sample data is an array of Person instances.
         * Let's organise it first by gender (IsMale), and then by Age.
         * Finally, we'll return a count. */
        var organised = people.Pivot(p => p.IsMale, p => p.Age, l => l.Count());

        Assert.IsTrue(organised.Count == 2, "More than two genders were returned.");
        Assert.IsTrue(organised[true].Count == 2, "More than two ages were returned for males.");
        Assert.IsTrue(organised[false].Count == 1, "More than 1 age was returned for females.");

        int count = organised[true][30];            
        Assert.IsTrue(count == 3, "There are more than 3 male 30 year olds in our data.");
    }

在这个测试用例中返回的是一个 Dictionary> 。实例。布尔值是 IsMale group by 的结果，在我们的示例数据中，正确返回 2 项，true 和 false。内部字典有一个年龄键和一个计数值。在我们的测试数据中，organized[true][30] 反映了集合中所有 30 岁的男性。

问题不在于数据透视函数本身，而是由于某种原因，当我们通过 NUnit 测试运行程序和 Resharper 的单元测试运行程序运行此函数时，测试失败，报告行“int count =organized[true][”的 KeyNotFoundException 30]；”。当我们调试此测试时，它正确返回值 3（在我们的示例数据中，我们有 3 名 30 岁的男性）。

有什么想法吗？

Answer 1

您是否尝试将 NUnit 配置为从 VS 内运行它（作为外部程序）？这样您就可以让 NUint 运行您的测试。在调试器下