Tests should be aware of the Current Culture Info

Hello,

As i'm French, my CultureInfo.CurrentCulture is set to "fr-FR" while running tests.
But for some tests, especially for the ToString() methods, tests are write to check "en-US" Culture.
All these concatenations can be replaced with something like:

`string.Format(CultureInfo.CurrentCulture, "<{1:c}{0} {2:c}{0} {3:c}{0} {4:c}>", separator, 2.5, 2, 3, 3.3);