This thread:
https://openacs.org/forums/message-view?message_id=155046 seems to summarize the state of online tests in OpenACS pretty well. My impression from it is that we have a bunch of survey packages with some features, and that a full-featured system doesn't exist for OpenACS but is being ported - ETA unknown.
Meanwhile, I put together a fairly simple app which does online testing and shows correct answers (and lets test-takers argue with the correct answers) and uploaded it to the repository just today. It's called "Vocabulary" and you can install it from the repository, or see it (with some sample data) at aufrecht.org/vocabulary. If a standard solution ever shows up in OpenACS, I'll modify my package to use it instead.
