allansimon/docker-postgres-for-testing repository overview

⁠Docker Postgres For Testing

This a docker image based in the official Postgres 9.4 docker image⁠ tweaked for database testing.

It basically configure things like turning off write ahead log (fsync=off) to make it faster. Notice that this can make the database more likely to be in an inconsistent state, if the case of a server crash. This is not a problem for database testing as we are more concerned with fast feedback and not about loosing data.

This is an alternative to H2⁠, in memory SQLite⁠ and HyperSQL⁠. You should consider this as it runs a real PostgreSQL server, that would be very close on what you have in production.

Check the file config.sh for all the configurations.

References:

• https://stackoverflow.com/questions/9407442/optimise-postgresql-for-fast-testing⁠
• http://michael.robellard.com/2015/07/dont-test-with-sqllite-when-you-use.html⁠

⁠Tips for writing tests

• Do all schema setup (DDL) once before running the tests
• Run the schema setup (DDL), as the DB migration that would run in production
• Avoid DDL in each test, as that tent to be very slow
• Before each test, truncate the tables and put some seed data (DML), that should be quick
• Remember fasts tests are important, slow tests make you avoid refactoring code!

⁠TODO

• Tweak shared_buffers
• Tweak work_mem