---
title: "Test patterns"
description: "What to test and how — which expectation when, finding problems with set is empty, smoke tests, comparing data across systems, incremental loads"
url: "https://docs.justcat.it/how-to-guides/test-patterns/"
---
# Test patterns


What to test and how. CAT has five expectations on purpose — you bring the SQL or DAX; these pages show the patterns that cover almost everything a data team needs to prove.