Dummy apps are located at tests/dummy, but addon authors may want to have multiple dummy apps, for example when testing the addon on Classic and MU layouts, or just having the possibility to have different dummy apps.

A possible solution would be to provide an option for the location of the dummy app.

ember serve --dummy mu-dummy
ember test --dummy mu-dummy

// or 

EMBER_CLI_DUMMY=mu-dummy ember serve
EMBER_CLI_DUMMY=mu-dummy ember test

• The dummy app must be located at tests/${dummyValue}
• The default value of the option is dummy

A dummy app (for example dummy2) in a different location must change:

//config/environment.js
    modulePrefix: 'dummy2'

Because this is an advanced case, I think, it would be ok if we just document it correctly, otherwise we would need to create a blueprint to create correctly a dummy app with a different name.

I am not sure what the current constraints are; I have open the issue for discussion.

Related

https://github.com/mansona/ember-cli-multiple-dummy-apps
https://github.com/mansona/testing-mu
#8322

/cc @mansona