Unit tests (jest)
Per discussion, worth compacting the display of materializations to one line, and perhaps including the path (this also gives a quick visual indication if something has been written locally vs. to S3)
This looks great to me! Nice visual improvement. It's definitely less generic if we break down "display events" into materializations + expectations and pass those two categories in explicitly, but that does allow for a more customized presentation of each type. I think an alternative would be to allow for display events to have children and do the disclosure triangles in a super generic way, but given that these are probably the two major categories it seems fine to just handle each one.
We should verify that we're OK with users not being able to throw arbitrary "display events" in that don't fall into one of the two categories.
Hah wow - can't believe I hadn't noticed this!