Re: [PATCH] qtest/migration: Add a test for the analyze-migration script

[Fabiano Rosas <farosas@suse.de>]

Thomas Huth <thuth@redhat.com> writes:

> On 27/09/2023 23.47, Fabiano Rosas wrote:
>> Add a smoke test that migrates to a file and gives it to the
>> script. It should catch the most annoying errors such as changes in
>> the ram flags.
>> 
>> After code has been merged it becomes way harder to figure out what is
>> causing the script to fail, the person making the change is the most
>> likely to know right away what the problem is.
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>> ---
>> I know this adds a python dependency to qtests and I'm not sure how
>> much we care about this script, but on the other hand it would be nice
>> to catch these errors early on.
>> 
>> This would also help with future work that touches the migration
>> stream (moving multifd out of ram.c and fixed-ram).
>> 
>> Let me know what you think.
>
> Without looking at this too closely, my first thought was: This sounds 
> rather like a good candidate for an avocado test instead. It's using Python, 
> so tests/avocado/ sounds like a better fit. Have you considered adding it as 
> an avocado test already?
>

I intended to keep all migration tests at the same place. And well, to
be honest, I have given up on avocado. Too unmaintained, incrutable
logging and last time I tried to use it locally, it was leaving stale
processes behind upon failure.

Of course, if that's the preferred place to put python tests I could do
it, but I don't find it too compelling.

>  >+#define ANALYZE_SCRIPT "tests/qtest/analyze-migration.py"
>
> Why can't you use scripts/analyze-migration.py directly?
>

I'm not entirely sure that's the case with QEMU, but generally build
directories can move/not be directly under the source tree. The test
wouldn't know from where to fetch the script.

>  >+    file = g_strdup_printf("%s/migfile", tmpfs);
>
> Please, no static file names for temporary files - tests might be running in 
> parallel, and then you get race conditions! Use something like 
> g_file_open_tmp() instead to create a file with a random name.
>

Ok, I can do that. However, if you look for "tmpfs" in migration-test.c
you'll see that's done all over the place. I'm thinking individual tests
under glib are never run in parallel. At least for the migration suite.