When a Fuchsia system downloads a software update the software delivery system is responsible for checking the signature of downloaded packages. This test simulates an update that contains a bad signature.
Detailed component composition is articulated in .cml files in the meta/ subdirectory. In general, the test brings up the hello_world_v0 system assembly in an isolated fshost and initiates an update to hello_world_v1 via an isolated netstack and pkg_server.