Re: [PATCH 2/2] test: Make log truncation test more robust

[Stefano Brivio <sbrivio@redhat.com>]

On Wed, 24 Apr 2024 14:30:00 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> test/pasta_options/log_to_file checks that pasta truncates its log file
> when started.  It does that by starting pasta with a log file once, then
> starting it again and checking that after the second round, the log file
> has only one line: the startup banner from the second invocation.
> 
> However, this test will break if the second invocation logs any additional
> messages at startup.  This can easily happen on a host with multiple
> network interfaces due to the "Multiple default route" informational
> messages added in 639fdf06e ("netlink: Fix selection of template
> interface").  I believe it could also happen on a host without IPv6
> connectivity due to the "Couldn't pick external interface" messages, though
> I haven't confirmed this.
> 
> Make the log file test more robust, by not testing for a single line, but
> instead explicitly testing for the PID of the second pasta invocation in
> the banner line.
> 
> Link: https://bugs.passt.top/show_bug.cgi?id=88
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  test/pasta_options/log_to_file | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/test/pasta_options/log_to_file b/test/pasta_options/log_to_file
> index f1002167..fe50e50b 100644
> --- a/test/pasta_options/log_to_file
> +++ b/test/pasta_options/log_to_file
> @@ -37,8 +37,9 @@ passt	./pasta -l __LOG_FILE__ -- /bin/true
>  check	[ -s __LOG_FILE__ ]
>  
>  test	Log truncated on creation
> -passt	./pasta -l __LOG_FILE__ -- /bin/true
> -check	[ $(cat __LOG_FILE__ | wc -l) -eq 1 ]
> +passt	./pasta -l __LOG_FILE__ -- /bin/true & wait
> +pout	PID2 echo $!
> +check	head -1 __LOG_FILE__ | grep '^pasta .* [(]__PID2__[)]$'
                                                       ^^^^^^^^^^^^^^

I'm mildly amused that this actually works. :)

-- 
Stefano