The `docker swarm update` copmmand does not have a `--quiet` flag, but this
test was trying to set it.
docker swarm update --help
Usage: docker swarm update [OPTIONS]
Update the swarm
Options:
--autolock Change manager autolocking setting (true|false)
--cert-expiry duration Validity period for node certificates (ns|us|ms|s|m|h) (default 2160h0m0s)
--dispatcher-heartbeat duration Dispatcher heartbeat period (ns|us|ms|s|m|h) (default 5s)
--external-ca external-ca Specifications of one or more certificate signing endpoints
--max-snapshots uint Number of additional Raft snapshots to retain
--snapshot-interval uint Number of log entries between Raft snapshots (default 10000)
--task-history-limit int Task history retention limit (default 5)
The test didn't catch this issue, because errors when setting the flag were
not handled, so also adding error-handling;
=== Failed
=== FAIL: cli/command/swarm TestSwarmUpdate (0.00s)
update_test.go:177: assertion failed: error is not nil: no such flag -quiet
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>