Re: [Qemu-devel] [PATCH 2/6] tests/device-introspection: Check that the qom-tree and qtree do not change

[Markus Armbruster <armbru@redhat.com>]

Thomas Huth <thuth@redhat.com> writes:

> Introspection should not change the qom-tree / qtree, so we should check
> this in the device-introspect-test, too. This patch helped to find lots
> of instrospection bugs during the QEMU v3.0 soft/hard-freeze period in the
> last two months.

Clever idea.

> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/device-introspect-test.c | 23 +++++++++++++++++++----
>  1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/tests/device-introspect-test.c b/tests/device-introspect-test.c
> index 0b4f221..5b7ec05 100644
> --- a/tests/device-introspect-test.c
> +++ b/tests/device-introspect-test.c
> @@ -103,7 +103,14 @@ static QList *device_type_list(bool abstract)
>  static void test_one_device(const char *type)
>  {
>      QDict *resp;
> -    char *help, *qom_tree;
> +    char *help;
> +    char *qom_tree_start, *qom_tree_end;
> +    char *qtree_start, *qtree_end;
> +
> +    g_debug("Testing device '%s'", type);

This is only the second use of g_debug() in tests/.  What are you trying
to accomplish?

> +
> +    qom_tree_start = hmp("info qom-tree");
> +    qtree_start = hmp("info qtree");
>  
>      resp = qmp("{'execute': 'device-list-properties',"
>                 " 'arguments': {'typename': %s}}",
> @@ -115,10 +122,18 @@ static void test_one_device(const char *type)
>  
>      /*
>       * Some devices leave dangling pointers in QOM behind.
> -     * "info qom-tree" has a good chance at crashing then
> +     * "info qom-tree" or "info qtree" have a good chance at crashing then.
> +     * Also make sure that the tree did not change.
>       */
> -    qom_tree = hmp("info qom-tree");
> -    g_free(qom_tree);
> +    qom_tree_end = hmp("info qom-tree");
> +    g_assert_cmpstr(qom_tree_start, ==, qom_tree_end);
> +    g_free(qom_tree_start);
> +    g_free(qom_tree_end);
> +
> +    qtree_end = hmp("info qtree");
> +    g_assert_cmpstr(qtree_start, ==, qtree_end);
> +    g_free(qtree_start);
> +    g_free(qtree_end);
>  }
>  
>  static void test_device_intro_list(void)

Output of "info qom-tree" depends on hash table iteration order, but
that could almost be considered a feature here.