Question 1

How does pg-mem compare to Docker for PostgreSQL testing?

Accepted Answer

pg-mem is faster and lighter since it runs in memory without container overhead, making it ideal for unit tests. However, Docker provides a full PostgreSQL instance with all features, better for integration testing where accuracy is key.

Question 2

Can I use pg-mem with TypeORM for testing?

Accepted Answer

Yes, pg-mem has a built-in adapter for TypeORM. You can create a pg-mem instance and configure TypeORM to use it, allowing you to run tests without a real database connection, as mentioned in the libraries adapters section.

Question 3

How to reset database state between tests in pg-mem?

Accepted Answer

Use the backup and restore feature. After setting up your schema and data, create a backup, then call restore() before each test to instantly rollback to that state, ensuring test isolation without reinitialization.

Question 4

Does pg-mem support all PostgreSQL data types?

Accepted Answer

No, pg-mem has limitations; for example, number types are handled as JavaScript numbers, which might not match PostgreSQL's precision. You can register custom types, but native support is incomplete, as noted in the current limitations.

Question 5

What if I need PostgreSQL extensions like uuid-ossp in pg-mem?

Accepted Answer

You must mock them manually. pg-mem doesn't support native extensions, but you can register custom functions or equivalent types to simulate extension behavior, though this requires extra development effort.

Question 6

Is pg-mem good for testing complex SQL queries with joins?

Accepted Answer

It's limited; pg-mem has basic index support and may not optimize joins effectively, potentially leading to catastrophic join optimizations. For complex queries, results might differ from real PostgreSQL, so verify carefully.

pg-mem

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