How to test C# code on many runtime versions?

Is there a framework or website or something that makes it possible to test C# code on many versions of .NET, specifically different versions of the system runtime library?

I've found System.TimeSpan.Parse("0:00:00.01000000") gives different results on different .NET implementations. Sometimes it throws an OverflowException, sometimes a FormatException, and sometimes it returns a 100ms TimeSpan (it's really 10ms).

I've submitted a patch to Microsoft already. But is there some easy way I can test this across different .NET implementations and different class libraries?

Here's a gist of the complete code I'd like to test, although I'm not sure it reports the .NET version information in a complete or useful way.