tests/boot_linux_console: refactor the console watcher into utility method
This introduces a utility method that monitors the console device and
looks for either a message that signals the test success or failure.
Signed-off-by: Cleber Rosa <crosa@redhat.com>
Reviewed-by: Caio Carrara <ccarrara@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <
20190312171824.5134-12-crosa@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>