This is obvious in hindsight, but I am writing this note in hopes that will help someone else.
I was looking for a way to see the SQL statements issued by my tests. I wasn't sure if that was something to be configured in ecto or postgrex.
Turns out, it is a phoenix configuration.
# config/test.exs # ... config :logger, level: :debug # ...
Thanks to Adam Rutkowski from the Phoenix Slack channel.