Testing against a gold master that is a nice, visual, representation of the data. I've seen this described as testing-concept-miniformats-for-test-input-and-output. In other words like I do for the epicify project where I basically made an easy to read, purpose-built, import and export format that I used to seed the data and validate the results.
This is similar to testing-concept-approval-tests
One interesting thing to do is to use the previous-interface-as-gold-master
Seems to also be called "snapshot" testing blog-post-jest-snapshot-testing
talk-observing-change-gold-master-test