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

[Fabiano Rosas <farosas@suse.de>]

Fabiano Rosas <farosas@suse.de> writes:

> 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.
> ---
>  tests/qtest/meson.build      |  6 +++++
>  tests/qtest/migration-test.c | 51 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 57 insertions(+)
>
> diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
> index 1fba07f4ed..d2511b3227 100644
> --- a/tests/qtest/meson.build
> +++ b/tests/qtest/meson.build
> @@ -301,6 +301,10 @@ if gnutls.found()
>    endif
>  endif
>  
> +configure_file(input: meson.project_source_root() / 'scripts/analyze-migration.py',
> +               output: 'analyze-migration.py',
> +               configuration: configuration_data())
> +
>  qtests = {
>    'bios-tables-test': [io, 'boot-sector.c', 'acpi-utils.c', 'tpm-emu.c'],
>    'cdrom-test': files('boot-sector.c'),
> @@ -356,6 +360,8 @@ foreach dir : target_dirs
>      test_deps += [qsd]
>    endif
>  
> +  qtest_env.set('PYTHON', python.full_path())
> +
>    foreach test : target_qtests
>      # Executables are shared across targets, declare them only the first time we
>      # encounter them
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index 1b43df5ca7..122089522f 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -66,6 +66,8 @@ static bool got_dst_resume;
>   */
>  #define DIRTYLIMIT_TOLERANCE_RANGE  25  /* MB/s */
>  
> +#define ANALYZE_SCRIPT "tests/qtest/analyze-migration.py"
> +
>  #if defined(__linux__)
>  #include <sys/syscall.h>
>  #include <sys/vfs.h>
> @@ -1486,6 +1488,52 @@ static void test_baddest(void)
>      test_migrate_end(from, to, false);
>  }
>  
> +#ifndef _WIN32
> +static void test_analyze_script(void)
> +{
> +    MigrateStart args = {};
> +    QTestState *from, *to;
> +    g_autofree char *uri = NULL;
> +    g_autofree char *file = NULL;
> +    int pid, wstatus;
> +    const char *python = g_getenv("PYTHON");
> +
> +    if (!python) {
> +        g_test_skip("PYTHON variable not set");
> +        return;
> +    }
> +
> +    /* dummy url */
> +    if (test_migrate_start(&from, &to, "tcp:127.0.0.1:0", &args)) {
> +        return;
> +    }
> +
> +    file = g_strdup_printf("%s/migfile", tmpfs);
> +    uri = g_strdup_printf("exec:cat > %s", file);
> +
> +    migrate_ensure_converge(from);
> +    migrate_qmp(from, uri, "{}");
> +    wait_for_migration_complete(from);
> +
> +    pid = fork();
> +    if (!pid) {
> +        close(1);
> +        open("/dev/null", O_WRONLY);
> +        execl(python, python, ANALYZE_SCRIPT,
> +              "-f", file, NULL);
> +        g_assert_not_reached();
> +    }
> +
> +    assert(waitpid(pid, &wstatus, 0) == pid);
> +    if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != 0) {
> +        g_test_message("Failed to analyze the migration stream");
> +        g_test_fail();

I just noticed that this is really nice because it fails the test
without aborting, so we get a nice line in the output like this:

▶  44/355 /x86_64/migration/analyze-script  FAIL

which means that if we could replace some asserts with g_test_fail in
the migration code we would actually see what failed without having to
look at the "ok" line in the log and guess what the next test was.

> +    }
> +    test_migrate_end(from, to, false);
> +    cleanup("migfile");
> +}
> +#endif
> +
>  static void test_precopy_common(MigrateCommon *args)
>  {
>      QTestState *from, *to;
> @@ -2828,6 +2876,9 @@ int main(int argc, char **argv)
>      }
>  
>      qtest_add_func("/migration/bad_dest", test_baddest);
> +#ifndef _WIN32
> +    qtest_add_func("/migration/analyze-script", test_analyze_script);
> +#endif
>      qtest_add_func("/migration/precopy/unix/plain", test_precopy_unix_plain);
>      qtest_add_func("/migration/precopy/unix/xbzrle", test_precopy_unix_xbzrle);
>      /*