I will soon be performing usability tests on a design prototype of a web app.
The proposed system, though, makes use of some advanced interactions that we probably won't be able to mock up in the prototype. Things like updating a graph on the fly based on data inputs, highlighting overlaps in the graph on the fly, etc.
What techniques exist to fake interactions in a prototype that's not fully functional?
In past tests like this I've used a Wizard of Oz technique, where an assistant generates feedback screens based on the user's input, and feeds them to the test screen. We might go that route, but I'm wondering what other techniques are available for a situation like this.