Broccoli‑fixture provides helpers for testing Broccoli plugins by allowing developers to define file‑system fixtures as plain JavaScript objects, turn those objects into Broccoli source nodes, and then build the nodes back into fixture objects without touching the real file system. It offers a `Node` class for creating fixture‑based sources, a `build` function (and a reusable `Builder` class) that returns promises with the resulting fixture trees, and is targeted at plugin authors who write automated tests for Broccoli build pipelines.