“ObservableCollection”方法的单元测试

Question

我是新来的，希望你能帮助我。 我有一个 WPF 应用程序，这是获取对象（在本例中为 TreeView）和 ItemSelectionChangedEventArgs（我在其中捕获当前文件夹）的方法。

public static ObservableCollection<Folder> OnSelectionChanged(object sender, ItemSelectionChangedEventArgs itemSelection)
    {
        if (sender == null)
        {
            throw new ArgumentNullException("Can't be null", nameof(sender));
        }
        if (itemSelection == null)
        {
            throw new ArgumentNullException("Can't be null", nameof(itemSelection));
        }

        var selected = itemSelection.AddedItems[0] as Folder;

        DirectoryInfo dirInfo = new DirectoryInfo(selected.FullName.ToString());
        ObservableCollection<Folder> directories = new ObservableCollection<Folder>();

        directories = AddDirectoryInfo(directories, dirInfo);
        directories = AddFileInfo(directories, dirInfo);
        
        return directories;
    }

我需要为这个方法编写单元测试，但是我尝试初始化参数以传输到这个方法中我有例外。

private readonly string _folderName = "C:\\NewTestFolder";
[TestMethod()]
    public void OnSelectionChangedTest()
    {
        var sender = new SfTreeView() { Name = "treeSize" };

       var itemSelection = new ItemSelectionChangedEventArgs()
        {
            AddedItems = { new Folder()
            {
                FullName = _folderName,
                HasChildrenNodes = false,
                Modified = DateTime.Now.ToString(),
                Name = "NewTestFolder",
                Size = "0",
                Type = "Folder"
            } },
            RemovedItems = { new Folder() { FullName = "" } }
        };


        var result = FolderView.OnSelectionChanged(sender, itemSelection);
    }

发件人给出错误：System.InvalidOperationException：'调用线程应该是 STA，因为大多数 UI 组件都需要它。'

itemSelection 给出错误：System.NullReferenceException：“对象引用未设置为对象的实例。”

也许我做错了什么，这些传递给方法的参数应该以其他方式设置。

Answer 1

首先，感谢@CharlesMager 的回答，我真的错过了我不需要“发件人”参数的事实。

对于这种情况，接下来它帮助了我，我创建了新类 ItemSelectionChangedEventArgs 并从当前基本类继承了他，然后我重新定义了变量 AdditionalItems 和 RemoveItems，因为在基本类中它们具有“内部集”，然后我初始化了新列表。

AddedItems = new List<object>()
{ 
    new Folder()
    {
        FullName = _folderName,
        HasChildrenNodes = false,
        Modified = DateTime.Now.ToString(),
        Name = "NewTestFolder",
        Size = "0",
        Type = "Folder"
    } 
},
RemovedItems = new List<object>()
{ 
    new Folder() 
}