Using Thread.Sleep() in unit test! A good idea?

gistfile1.cs

[Test]
public void Execute_ImportSuccessFulWithoutModifiedText_ExpectNoModelChangedMessageSent()
{
    //Arrange
    var importCommand = makeImportAllTextsCommand(new ImportStatistics {ImportedCount = 0});

    var messageSent = false;
    Messenger.Default.Register<ModelChangedMessage>(this, message => messageSent = true);

    //Act
    importCommand.Execute(null);
    importCommand.TaskSUT.Wait();

    //Assert
    Assert.That(messageSent, Is.False);
}

private static ImportAllTextsCommandSUT makeImportAllTextsCommand(ImportStatistics importStatisticsToReturn)
{
    var fileDialog = MockRepository.GenerateStub<IFileDialog>();
    fileDialog.Stub(dialog => dialog.ShowOpenFileDialog(null)).IgnoreArguments().Return("c:\texts.xlsx");

    var excelService = MockRepository.GenerateStub<IExcelService>();
    excelService
        .Stub(service => service.Import("c:\texts.xlsx"))
        .IgnoreArguments()
        .Return(importStatisticsToReturn);

    var importCommand = new ImportAllTextsCommandSUT(excelService, fileDialog);
    return importCommand;
}

private class ImportAllTextsCommandSUT : ImportAllTextsCommand
{
    public ImportAllTextsCommandSUT(IExcelService excelService, IFileDialog fileDialog) : base(excelService, fileDialog)
    {
    }

    public Task TaskSUT
    {
        get { return Task; }
    }
}