Re: [Qemu-devel] [PATCH v14 09/19] tests: Add check-qnull

[Markus Armbruster <armbru@redhat.com>]

Eric Blake <eblake@redhat.com> writes:

> Add a new test, for checking reference counting of qnull(). As
> part of the new file, move a previous reference counting change
> added in commit a861564 into a more logical place.

into or to?  Those darn prepositions...

> Signed-off-by: Eric Blake <eblake@redhat.com>
>
> ---
> v14: no change
> v13: no change
> v12: new patch
> ---
>  tests/check-qnull.c             | 60 +++++++++++++++++++++++++++++++++++++++++
>  tests/test-qmp-output-visitor.c |  2 --
>  tests/.gitignore                |  1 +
>  tests/Makefile                  |  6 ++++-
>  4 files changed, 66 insertions(+), 3 deletions(-)
>  create mode 100644 tests/check-qnull.c
>
> diff --git a/tests/check-qnull.c b/tests/check-qnull.c
> new file mode 100644
> index 0000000..b0fb1e6
> --- /dev/null
> +++ b/tests/check-qnull.c
> @@ -0,0 +1,60 @@
> +/*
> + * QNull unit-tests.
> + *
> + * Copyright (C) 2016 Red Hat Inc.
> + *
> + * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
> + * See the COPYING.LIB file in the top-level directory.
> + */
> +#include "qemu/osdep.h"
> +#include <glib.h>
> +
> +#include "qapi/qmp/qobject.h"
> +#include "qemu-common.h"
> +#include "qapi/qmp-output-visitor.h"
> +
> +/*
> + * Public Interface test-cases
> + *
> + * (with some violations to access 'private' data)
> + */
> +
> +static void qnull_ref_test(void)
> +{
> +    QObject *obj;
> +
> +    g_assert(qnull_.refcnt == 1);
> +    obj = qnull();
> +    g_assert(obj);
> +    g_assert(obj == &qnull_);

This one's an implementation detail, but the reference count checks that
follow need to rely on it.  Okay.

> +    g_assert(qnull_.refcnt == 2);
> +    g_assert(qobject_type(obj) == QTYPE_QNULL);
> +    qobject_decref(obj);
> +    g_assert(qnull_.refcnt == 1);
> +}
> +
> +static void qnull_visit_test(void)
> +{
> +    QObject *obj;
> +    QmpOutputVisitor *qov;
> +
> +    g_assert(qnull_.refcnt == 1);
> +    qov = qmp_output_visitor_new();
> +    /* FIXME: Empty visits are ugly, we should have a visit_type_null(). */
> +    obj = qmp_output_get_qobject(qov);
> +    g_assert(obj == &qnull_);
> +    qobject_decref(obj);
> +
> +    qmp_output_visitor_cleanup(qov);
> +    g_assert(qnull_.refcnt == 1);
> +}
> +
> +int main(int argc, char **argv)
> +{
> +    g_test_init(&argc, &argv, NULL);
> +
> +    g_test_add_func("/public/qnull_ref", qnull_ref_test);
> +    g_test_add_func("/public/qnull_visit", qnull_visit_test);
> +
> +    return g_test_run();
> +}
[...]

Nice & simple patch, welcome relief after the big & subtle PATCH 08.