in a test I'm doing I'm looking for a div of class errorExplanation to
know if an update passed validation, but even if the rendered html has
it, as you can see below, the assert_tag fails. What am I doing wrong?
assert_tag is quite literally looking for a div tag of that class,
inserting such a tag, but assert_tag doesn't understand that.
You probably want to use assert_select_rjs (I also find the arts
plugin useful for this sort of stuff)