Test fixtures for kmptoolkit-downloader: FakeDownloader for testing code that merely asks for a resource, FakeDownloaderStorage for testing storage-facing code, plus a recording notifier, an in-memory DownloadStateStore, a test-only unit/group catalogue, and a virtual-clock DownloadDispatchers so a stall timeout costs no real time. Pick this module as a testImplementation dependency alongside kmptoolkit-downloader.