Chip brought up a good point on the https://codex.wordpress.org/Theme_Unit_Test named XML file — it always looks out of date because of the naming.
I renamed it to theme-unit-test-data.xml to avoid that confusion.
It gets updated fairly frequently, probably once a month to fix 404s and add new test data, so when that happens I’ll update the text on the Codex page to the current date and time to reflect that.
It’s fresh today from the latest export of http://wpthemetestdata.wordpress.com/ — including a quick cleanup to remove unneeded
wp:postmeta nodes for values of