You can try using the #if DEBUG
syntax like so:
#if DEBUG
private string StringGenerator()
{
Guid g = Guid.NewGuid();
string guidString = Convert.ToBase64String(g.ToByteArray());
guidString = guidString.Replace("=", "");
guidString = guidString.Replace("+", "");
return guidString;
}
#else
private string StringGenerator()
{
Guid g = Guid.NewGuid();
string guidString = Convert.ToBase64String(g.ToByteArray());
return guidString;
}
#endif
However, there are some differences with using this. See this question for more details.