This package gives you the capability to create as many fixtures to represent as many mock instances of e.g. SQLite, Postgres, Mongo, etc might actually exist in your system.

Furthermore, you can prepopulate the connections those fixtures yield to you with whatever DDL, preset data, or functions you might require.

A new resource (database or otherwise) is created on a per test database, which allows each fixture to be used in multiple tests without risking data leakage or side-effects from one test to another.


By default the underlying containers are reused across tests to amortize the container startup cost. Tests then create new “resources” (e.g. databases) within that container to avoid inter-test pollution.

This can cause inter-test dependencies if your tests are altering container-global resources like database users. In the event this is a problem, resources can be configured to not be session fixtures, although this will likely be drastically slower overall.

See Config for information on customizing the configuration for docker-based fixtures.