pytest-orm-boundaries 0.1.0

Pytest plugin that fails your tests when ORM queries cross DDD aggregate boundaries (Django supported today).

pytest-orm-boundaries

A pytest plugin that fails your tests when ORM queries cross your DDD aggregate boundaries.

Currently works with Django ORM.

In domain-driven design, an aggregate is a consistency boundary: code in one aggregate should not reach into the internals of another. Django's __ relation lookups make it easy to cross those boundaries silently:

# Payment and Order belong to different aggregates — this query couples them.
Purchase.objects.get(client__name="John")

pytest-orm-boundaries watches the queries your test suite executes and reports the ones that step outside their aggregate, including __, subqueries and other.

Install

pip install pytest-orm-boundaries

pytest picks the plugin up automatically.

Configure

Declare your aggregates in boundaries.toml at the project root (or point at the file with --boundaries-config / the boundaries_config ini option):

[aggregates]
client   = ["bookshop.Client"]
book     = ["bookshop.Book"]
purchase = ["bookshop.Purchase", "bookshop.PurchaseLine"]

Models are written as app_label.Model. Models not listed in any aggregate are not checked. Without a config file the plugin emits a warning and runs no checks.

Status

Alpha - testing basic version.