How do you use joinTest?

How do you use joinTest in the meeting web sdk? I’d like to understand how this works. If it’s a test meeting why is a meeting number required?

Which Web Meeting SDK version?
3.7.0

Bump. Are there any examples?

Bump again. Anyone?? I figured this would be a simple one to answer.

Bump again. Seeing this error:

You are join an normal meeting use joinTest, please switch join