Styjun

I am refactoring some unit tests and found out that some parsing strategies rely on DateTime.TryParseExact and sbyte.TryPase which themselves rely on NumberFormatInfo.CurrentInfo and DateTimeFormatInfo.CurrentInfo.

In order to make my unit tests properly arranged, I decided to setup the CurrentInfo property of both NumberFormatInfo and DateTimeFormatInfo to their invariant flavours through:

CultureInfo.CurrentCulture = CultureInfo.InvariantCulture;

However, out of curiosity I tried to check whether the respective InvariantInfo were setup through a unit test and turns out that no, they are not. I am wondering what I am missing here to have the InvariantCulture enforced in those those two 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);

Knowing that the underlying implementations:

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));
 

If I understand you right, you want to run some code (tests) under culture which is Current one, except NumberFormat and DateTimeFormat which are Invariant. If it's your case, I suggest to Clone the current culture and modify the clone:

// 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;

Let's have a look at formats

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

Outcome:

Equals

Edit: In order to run code using the modified culture we can implement a class for it:

 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);
 

And then use it as follows:

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