如何将DateTimeFormatInfo.CurrentInfo和NumberFormatInfo.CurrentInfo设置为不变？

Question

我正在重构一些单元测试，发现一些解析策略依赖于DateTime.TryParseExact和sbyte.TryPase，它们本身依赖于NumberFormatInfo.CurrentInfo和DateTimeFormatInfo.CurrentInfo。

为了使我的单元测试得到适当的安排，我决定通过以下方法将NumberFormatInfo和DateTimeFormatInfo的DateTimeFormatInfo属性设置为它们不变的味道：

CultureInfo.CurrentCulture = CultureInfo.InvariantCulture;

然而，出于好奇，我试图通过一个单元测试来检查各自的InvariantInfo是否被设置，结果发现不，它们不是。我想知道在这两个CurrentInfo中，我缺少了什么来执行CurrentInfo

[Fact]
public void ShouldReturnInvariantInfo()
{
    CultureInfo.CurrentCulture.NumberFormat = NumberFormatInfo.InvariantInfo;
    CultureInfo.CurrentCulture.DateTimeFormat = DateTimeFormatInfo.InvariantInfo;
    NumberFormatInfo.CurrentInfo.Should().Be(NumberFormatInfo.InvariantInfo);
    DateTimeFormatInfo.CurrentInfo.Should().Be(DateTimeFormatInfo.InvariantInfo);
}

知道基本的实现：

NumberFormatInfo.InvariantInfo

public static NumberFormatInfo CurrentInfo
{
  get
  {
    CultureInfo currentCulture = CultureInfo.CurrentCulture;
    if (!currentCulture._isInherited)
    {
      NumberFormatInfo numInfo = currentCulture.numInfo;
      if (numInfo != null)
        return numInfo;
    }
    return (NumberFormatInfo) currentCulture.GetFormat(typeof (NumberFormatInfo));
  }
}

DateTimeFormatInfo.CurrentInfo

public static DateTimeFormatInfo CurrentInfo
{
  get
  {
    CultureInfo currentCulture = CultureInfo.CurrentCulture;
    if (!currentCulture._isInherited)
    {
      DateTimeFormatInfo dateTimeInfo = currentCulture.dateTimeInfo;
      if (dateTimeInfo != null)
        return dateTimeInfo;
    }
    return (DateTimeFormatInfo) currentCulture.GetFormat(typeof (DateTimeFormatInfo));
  }
}

Answer 1

如果我对您的理解是正确的，您希望在区域性下运行一些代码(测试)，它是Current one，除了NumberFormat和DateTimeFormat，它们是Invariant。如果是您的情况，我建议Clone当前的文化并修改克隆：

// Current culture clone
CultureInfo testCulture = CultureInfo.CurrentCulture.Clone() as CultureInfo;

// modified: current culture except Number and DateTime which are Invariant
testCulture.NumberFormat = CultureInfo.InvariantCulture.NumberFormat;
testCulture.DateTimeFormat = CultureInfo.InvariantCulture.DateTimeFormat;

// and, finally, set back as current
CultureInfo.CurrentCulture = testCulture;

让我们看一下格式

Console.Write(ReferenceEquals(CultureInfo.CurrentCulture.DateTimeFormat,
                              CultureInfo.InvariantCulture.DateTimeFormat) 
     ? "Equals" 
     : "Not Equals");

结果：

Equals

编辑：为了运行代码using修改后的区域性，我们可以为它实现一个类：

  public class TestCulture : IDisposable {
    private CultureInfo m_SavedCulture; 
    private CultureInfo m_TestCulture;
    private bool m_IsDisposed;

    public TestCulture() {
      m_SavedCulture = CultureInfo.CurrentCulture; 

      m_TestCulture = CultureInfo.CurrentCulture.Clone() as CultureInfo;
      m_TestCulture.NumberFormat = CultureInfo.InvariantCulture.NumberFormat;
      m_TestCulture.DateTimeFormat = CultureInfo.InvariantCulture.DateTimeFormat;

      CultureInfo.CurrentCulture = m_TestCulture;
    }

    protected vitrual void Dispose(bool disposing) {
      if (disposing) {
        if (!m_IsDisposed && ReferenceEquals(CultureInfo.CurrentCulture, m_TestCulture)) {
          CultureInfo.CurrentCulture = m_SavedCulture;

          m_IsDisposed = true;
        }
      }
    }

    public void Dispose() => Dispose(true);
  }

然后按以下方式使用：

  using (new TestCulture()) {
    // Tests which should be run under the specific culture
  }