AB Test built with the Test Creator allows user to progress without selecting an option

[wil-j-wil]

When using the test creator for an AB test, there's no way to force the user to select an option before progressing.

I noticed in the examples that this was enforced using the 'scalerange' option with a custom error message. But there's no way to build this using the test creator, I have to add it in manually. Even using the 'Enforce a scale usage' option doesn't work when 'Interface' type is AB.

[nickjillings]

I guess the default behaviour really should be one of the shown options must be selected to continue anyway. @BrechtDeMan do you agree?

[BrechtDeMan]

I'd say either

1. One of the shown options must be selected to continue, but there is the option to also add a 'neither' button; or
2. the options can be left blank, but there is an option to enforce answering (like it is now except it doesn't work) - this could be by overriding the scalerange behaviour, or by introducing a new function, whichever is more semantic/elegant etc.

In some cases one should be able to select nothing at all, e.g. 'I don't hear a difference', 'I don't have a preference', etc.