testcontainers is a cool crate. It basically allows you to launch a container to test against in your unit tests.

My use-case was when integrating Postgres+Diesel for persisting our data.
I really wanted to make sure that we can save our data into there and load it back out in identical form.
And yeah, rather than writing some elaborate scripts to do a full-blown integration test, it's three lines of code with this crate to launch a Postgres container and have it cleaned up after the test.

Diesel is also quite cool here when you've got your migrations embedded, as it will automatically set up your database schema in the blank Postgres.