When server authentication is used, some test cases may require users that have certain permissions. Therefore there is a need to map certain VUs' credentials to certain test cases. In StresStimulus, this is implemented using User Groups. Every VU credential is assigned to a user group, and every test case runs with a selected user group. Here is how to use these user group:

1. In the Authentication section, input all the credentials.
2. Click the User Groups checkbox to show the User Group column. 
3. In each credential record, write in the group name that the record will belong to.
   
   
   
   
4. In the Managing Test Case section, select a test case (or test case group) and set the User Group property to the group name that this Test Case will use.