Instead of every module having to come up with a set of test methods for
the event bus, this handful of test helpers hides a lot of the needed
setup for the testing of the event bus.
The tests in portmapper is also ported over to the new helpers.
Updates #15160
Signed-off-by: Claus Lensbøl <claus@tailscale.com>
Enables monitoring events as they flow, listing bus clients, and
snapshotting internal queues to troubleshoot stalls.
Updates #15160
Signed-off-by: David Anderson <dave@tailscale.com>
The Client carries both publishers and subscribers for a single
actor. This makes the APIs for publish and subscribe look more
similar, and this structure is a better fit for upcoming debug
facilities.
Updates #15160
Signed-off-by: David Anderson <dave@tailscale.com>
