c# - 单元测试异步方法

Question

我在单元测试异步方法时遇到了一些问题。

这是我的单元测试代码:

        [TestMethod]
    public async Task TestRefreshList_RefreshesList()
    {
        int countBeforeAdd = listViewModel.NotesTitles.Count;

        // Add a note.
        await listViewModel.NoteRepository.AddNoteAsync(new Note { Title = String.Empty, Content = String.Empty });

        // Refresh.
        await listViewModel.RefreshList();

        int countAfterAdd = listViewModel.NotesTitles.Count;

        // Assert that the count increased by 1 and that it matches the count of the repository.
        Assert.IsTrue(countAfterAdd == countBeforeAdd + 1 && countAfterAdd == mockNoteRepository.FakeNotes.Count);
    }

当我运行这个测试时，它似乎永远不会通过第一个 await 语句。如果有帮助，以下是正在测试的方法:

    public ObservableCollection<Note> FakeNotes { get; set; }

    public Task AddNoteAsync(Models.Note note)
    {
        return new Task(() => 
        {
            FakeNotes.Add(note);
        });
    }

    public Task<ObservableCollection<string>> GetAllNoteTitlesAsync()
    {
        // Return the titles of the notes in the FakeNotes collection.
        return new Task<ObservableCollection<string>>(() =>
        {
            return new ObservableCollection<string>(FakeNotes.Select(n => n.Title));
        });
    }

....

        public async Task RefreshList()
    {
        try
        {
            NotesTitles = await NoteRepository.GetAllNoteTitlesAsync();
        }
        catch (Exception)
        {
            Notifier.Notify("We encountered an error when trying to load your notes. Please try again. ", "Ooops!");
        }
    }

如有任何帮助，我们将不胜感激。谢谢。

Answer 1

您的任务从未开始。尝试使用 Task.Run 而不是 Task 构造函数。