Minimal Test Data

Bache’s name for what Meszaros called the Minimal Fixture: use the smallest, simplest data that exercises the behavior under test. Rainsberger’s test is the sharpest: if you can change a value without changing the result, it’s irrelevant data, and irrelevant data actively hurts, because every reader must first figure out which fields matter.

The Test Data Builder pattern (Pryce) is the standard lever: sensible defaults, per-test overrides for the one or two values the behavior turns on. Serves both Fast and Readable.

Part of Test Desiderata.

Measuring: fixture-read coverage (fields the test never reads are bloat) and fixture-size trend over time.