如何使用單元測試聲明Linq集合

Question

我已經用LinQ編寫了簡單的分組

public IList dividedNumbersto5(IEnumerable<int> NumberOfCollection)
{
    IList reminderNumber = NumberOfCollection.ToList().GroupBy(g => g%5).OrderBy(g=>g.Key)
        .Select(g => new { Numbers = g, Remindar = g.Key}).ToList();
    return reminderNumber;                              
}

當我嘗試測試它時，它說第一個索引項目與我的期望不匹配。

var groupingoperators = new GroupingOperators();
IEnumerable<int> numberOfCollection = new List<int>{ 5,14,9,8};
IList remindernumber = groupingoperators.dividedNumbersto5(numberOfCollection);
IList expectedNumberCollection = new List<int>{0,3,4};
CollectionAssert.AreEqual(expectedNumberCollection, remindernumber);

CollectionAssert.AreEqual失敗。 （索引為0的元素不匹配。）

我不知道該如何編寫測試。

Answer 1

測試失敗的原因是因為：

"Two collections are equal if they have the same elements 
   in the same order and quantity."

資源

基本上，您需要更好地模擬第二個收藏集。 我認為這應該工作：

IList expectedNumberCollection = new List<object>{
 new {Numbers = new List<int>{5},Remindar=0},
 new {Numbers = new List<int>{8},Remindar=3}, 
 new {Numbers = new List<int>{14,9},Remindar=4}
};

Answer 2

首先- 您真的不應該從方法中返回匿名類型對象！ 以后在任何地方都很難用這種返回值執行任何操作。

我將創建一個名為Devided的新結構：

public struct Devided
{
    public int Reminder { get; set; }
    public List<int> Numbers { get; set; }

    public override bool Equals(object obj)
    {
        if(!(obj is Devided))
            return false;

        var d = (Devided)obj ;

        if(object.ReferenceEquals(this, d))
            return true;

        return this.Reminder == d.Reminder && this.Numbers.SequenceEqual(d.Numbers);
    }

    public override int GetHashCode()
    {
        return Reminder;
    }
}

我已經覆蓋了Equals和GetHashCode來使CollectionAssert起作用。

使用Devided類，您可以將方法返回類型更改為通用IList<Devided> ：

public static IList<Devided> dividedNumbersto5(IEnumerable<int> NumberOfCollection)
{
    IList<Devided> reminderNumber = NumberOfCollection.ToList().GroupBy(g => g % 5).OrderBy(g => g.Key)
        .Select(g => new Devided { Numbers = g.ToList(), Reminder = g.Key }).ToList();
    return reminderNumber;
}

並斷言測試：

[TestMethod]
public void TestMethod1()
{
    IEnumerable<int> numberOfCollection = new List<int> { 5, 14, 9, 8 };
    IList remindernumber = dividedNumbersto5(numberOfCollection);
    IList expectedNumberCollection = new List<Devided>
    {
        new Devided { Numbers = new List<int>() { 5 }, Reminder = 0 },
        new Devided { Numbers = new List<int>() { 8 }, Reminder = 3 },
        new Devided { Numbers = new List<int>() { 14, 9 }, Reminder = 4 }
    };

    CollectionAssert.AreEqual(expectedNumberCollection, remindernumber);
}

如果您要執行以下操作，則只能檢查Reminder ：

var expectedNumberCollection = new List<int> { 0, 3, 4 };

Assert.IsTrue(expectedNumberCollection.SequenceEqual(remindernumber.Select(x => x.Reminder)));