How to find path of active app.config file?

Question

I'm trying to finish this exception handler:

if (ConfigurationManager.ConnectionStrings["ConnectionString"]==null)
{
    string pathOfActiveConfigFile = ...?
    throw new ConfigurationErrorsException(
       "You either forgot to set the connection string, or " +
       "you're using a unit test framework that looks for  "+
       "the config file in strange places, update this file : " 
       + pathOfActiveConfigFile);
}

This problem seems to only happen to me when I'm using nUnit.

Answer 1

For .Net Framework, try this

AppDomain.CurrentDomain.SetupInformation.ConfigurationFile

For .Net core or anything newer, see the other answers.