C# 无法使用测试属性在 if 条件下获取数据

我正在尝试通过 [Teardown] 属性添加一些 txt 文件格式的文本，它会检查测试用例是通过还是失败，并相应地将数据添加到文本文件中。通过或失败由 if-else 条件检测。其他条件（通过测试）工作正常。但是当我与失败的测试捆绑在一起时，它没有给出预期的结果

对于通过的测试 - 结果

Test Case No.: 12345
Test Details: For test purpose
Start Time: 3/2/2016 3:51:28 PM
End Time: 3/2/2016 3:51:31 PM
Total Time: 0 minutes and 2 seconds
Status: Passed

对于失败的测试 - 结果

Test Case No.: 
Test Details: 
Start Time: 3/2/2016 3:49:37 PM
End Time: 1/1/0001 12:00:00 AM
Total Time: -49 minutes and -37 seconds
Status: Failed

从失败的测试结果来看，我没有低于以下内容

1. 测试用例编号
2. 测试详情：
3. 结束时间：
4. 总时间：

下面是我的代码：

[TestFixture(typeof(FirefoxDriver))]
[TestFixture(typeof(InternetExplorerDriver))]
[TestFixture(typeof(ChromeDriver))]
public class TestWithMultipleBrowsers<TWebDriver> where TWebDriver : IWebDriver, new()
{
    static DateTime _timestamp1;
    static DateTime _timestamp2;
    static string _TestNum;
    static string _TestDetails;
[Test]
public void SurfGoogle()
{
    _timestamp1 = DateTime.Now;
    TWebDriver driver = new TWebDriver();
   driver.Navigate().GoToUrl("http://www.google.com");
  //driver.FindElement(By.Id("q"));
   _timestamp2 = DateTime.Now;
   _TestNum = "12345";
   _TestDetails = "For test purpose";
}

[TearDown]
public void teardown()
{
    string path = (@"..'..'Result'");
    TimeSpan timediff = _timestamp2 - _timestamp1;
    string TotalTime = timediff.Minutes + " minutes and " + timediff.Seconds + " seconds";
    if (TestContext.CurrentContext.Result.Status == TestStatus.Failed)
    {
        string status = "Failed";
        File.WriteAllText(Path.Combine(path, "Failed" + ".txt"), "Test Case No.: " + _TestNum + string.Format(Environment.NewLine) + "Test Details: " + _TestDetails + string.Format(Environment.NewLine) + "Start Time: " + _timestamp1 + string.Format(Environment.NewLine) + "End Time: " + _timestamp2 + string.Format(Environment.NewLine) + "Total Time: " + TotalTime + string.Format(Environment.NewLine) + "Status: " + status);
    }
    else
    {
        string status = "Passed";
        File.WriteAllText(Path.Combine(path, "Passed" + ".txt"), "Test Case No.: " + _TestNum + string.Format(Environment.NewLine) + "Test Details: " + _TestDetails + string.Format(Environment.NewLine) + "Start Time: " + _timestamp1 + string.Format(Environment.NewLine) + "End Time: " + _timestamp2 + string.Format(Environment.NewLine) + "Total Time: " + TotalTime + string.Format(Environment.NewLine) + "Status: " + status);
    }   
  }
}

要使测试失败，您可以从我的代码中删除注释部分。

使用NUnit：2.6.4

[Test]
public void SurfGoogle()
{
    _timestamp1 = DateTime.Now;  
    _TestNum = "12345";                  <-------
    _TestDetails = "For test purpose";   <-------
    TWebDriver driver = new TWebDriver();
    driver.Navigate().GoToUrl("http://www.google.com");
    driver.FindElement(By.Id("q"));
  }
}
[TearDown]
public void teardown()
{
    string path = (@"..'..'Result'");
    _timestamp2 = DateTime.Now;          <-------
    TimeSpan timediff = _timestamp2 - _timestamp1;
    string TotalTime = timediff.Minutes + " minutes and " + timediff.Seconds + " seconds";
    if (TestContext.CurrentContext.Result.Status == TestStatus.Failed)
    {
        string status = "Failed";
        File.WriteAllText(Path.Combine(path, "Failed" + ".txt"), "Test Case No.: " + _TestNum + string.Format(Environment.NewLine) + "Test Details: " + _TestDetails + string.Format(Environment.NewLine) + "Start Time: " + _timestamp1 + string.Format(Environment.NewLine) + "End Time: " + _timestamp2 + string.Format(Environment.NewLine) + "Total Time: " + TotalTime + string.Format(Environment.NewLine) + "Status: " + status);
    }
    else
    {
        string status = "Passed";
        File.WriteAllText(Path.Combine(path, "Passed" + ".txt"), "Test Case No.: " + _TestNum + string.Format(Environment.NewLine) + "Test Details: " + _TestDetails + string.Format(Environment.NewLine) + "Start Time: " + _timestamp1 + string.Format(Environment.NewLine) + "End Time: " + _timestamp2 + string.Format(Environment.NewLine) + "Total Time: " + TotalTime + string.Format(Environment.NewLine) + "Status: " + status);
    }   
  }