冠名不当的借口:如果有人可以更好地描述它,请这样做。
我有一个WeakList<T>
类,它基本上是一个List<WeakReference<T>>
(尽管从字面意义上讲不是从列表派生的,但对用户来说应该是完全透明的)。
现在的基本思想是“如果引用的变量不存在,则忽略项目”,即WeakList<T>
源的一部分是:
public class WeakList<T> : IReadOnlyList<T>, IWeakList<T>, IWeakCollection<T>, IReadOnlyCollection<T>,
ICollection<T>, IEnumerable<T>, IEnumerable where T : class
{
private readonly List<WeakReference<T>> _myList;
public void Add(T item) {
_myList.Add(new WeakReference<T>(item));
}
IEnumerator<T> IEnumerable<T>.GetEnumerator() {
foreach (var reference in _myList) {
T elem;
if (reference.TryGetTarget(out elem)) {
yield return elem;
}
}
}
}
我仍然在考虑
List
在这里是否真的有意义,弱列表[n]并不总是与通过迭代到第n个元素得到它相同。 -是否有一个有命令但没有基于索引的访问的集合名称?但是除此之外:
该类还包括“清除”功能,旨在“删除不再存在的引用”。
public void Purge() {
for (int i = _myList.Count - 1; i >= 0; i--) {
T elem;
if (!_myList[i].TryGetTarget(out elem)) {
_myList.RemoveAt(i);
}
}
}
现在我的问题是:如何在单元测试(对于Nunit)中测试上述方法?如何设置列表,然后确保已删除某些元素,然后调用清除并对其进行测试,如下所示:
[TestFixture]
public class WeakListTests
{
[Test]
public static void PurgeTest() {
var myList = new WeakList<string>;
string s1 = "hello world 1";
string s2 = "hello world 2";
string s3 = "hello world 3";
myList.Add(s1);
myList.Add(s2);
myList.Add(s3);
// "clear", force s1 & s2 away. (yet keep a reference so I can test it gets removed)
myList.Purge();
Assert.That(myList, Does.Not.Contain(s1));
Assert.That(myList, Does.Not.Contain(s2));
Assert.That(myList, Does.Contain(s3));
}
}
该评论描述了我被困在哪一点。
最佳答案
您可以这样操作(请参阅评论):
[TestFixture]
public class WeakListTests
{
[Test]
public static void PurgeTest()
{
var myList = new WeakList<string>();
// construct strings like this to prevent interning
string s1 = new string(new[] { 'h', 'e', 'l', 'l', 'o' });
string s2 = new string(new[] { 'h', 'e', 'l', 'l', 'o', '2' });
// this string can be interned, we don't want it to be collected anyway
string s3 = "hello world 3";
myList.Add(s1);
myList.Add(s2);
myList.Add(s3);
// set to null for that to work even in application built with "Debug"
// in Release it will work without setting to null
s1 = null;
s2 = null;
// force GC collection
GC.Collect(2, GCCollectionMode.Forced);
// now s1 and s2 are away
myList.Purge();
// invoke your enumerator
var left = myList.ToArray();
// should contain 1 item and that item should be s3
Assert.That(left.Length == 1);
Assert.AreEqual(s3, left[0]);
}
}