Heroku PostGres Database suddenly empty [on hold]

I ran rails test on Heroku and it passed and I went about my day, only to start getting error reports from my alpha users. Turned out the database is empty except a few (not even all) fixtures.

Did the test destroy my production data base? Or am I somehow currently connecting to the test database instead? How can I debug this? How can I fix this? And I can avoid doing this in the future?