public void Test_VariablePathBrowsing_FileUntyped()
{
IFilePath file = @"$(Var)\File.txt".ToVariableFilePath();
Assert.IsTrue(file.GetBrotherFileWithName("MyFile.exe").ToString() == @"$(Var)\MyFile.exe");
Assert.IsTrue(file.GetBrotherDirectoryWithName("Dir").ToString() == @"$(Var)\Dir");
Assert.IsTrue(file.UpdateExtension(".bin").ToString() == @"$(Var)\File.bin");
}