On Mon, Mar 02, 2026 at 12:52:10PM +0100, Markus Armbruster wrote:
> Akihiko Odaki <[email protected]> writes:
>
> > A string that represents a double can be long if it is an exponentially
> > large number.
> >
> > Signed-off-by: Akihiko Odaki <[email protected]>
> > ---
> > tests/unit/test-qobject-input-visitor.c | 2 +-
> > tests/unit/test-qobject-output-visitor.c | 2 +-
> > 2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/tests/unit/test-qobject-input-visitor.c
> > b/tests/unit/test-qobject-input-visitor.c
> > index 84bdcdf702e0..baff9243313c 100644
> > --- a/tests/unit/test-qobject-input-visitor.c
> > +++ b/tests/unit/test-qobject-input-visitor.c
> > @@ -583,7 +583,7 @@ static void
> > test_visitor_in_list_struct(TestInputVisitorData *data,
> >
> > i = 0;
> > for (num_list = arrs->number; num_list; num_list = num_list->next) {
> > - char expected[32], actual[32];
> > + char expected[318], actual[318];
>
> Where does 318 come from?
If we're concerned about buffer sizes being too short, then that
is a strong sign we should be using g_strdup_printf instead of
sprintf with a bigger magic size.
As you say below though, it is better if we eliminate the string
formatting entirely here since it is irrelevant for the goals of
this test.
>
> >
> > sprintf(expected, "%.6f", (double)i / 3);
> > sprintf(actual, "%.6f", num_list->value);
> g_assert_cmpstr(expected, ==, actual);
> i++;
> }
>
> Existing code is safe, because the numbers run from 0, 1.0/3, ...,
> 31.0/3.
>
> Its purpose is to check the input visitor parses number arrays
> correctly. Doing it this way is questionable. Elsewhere in this file,
> we get away with the equivalent of
>
> g_assert_cmpfloat(num_list->value, ==, (double)i / 3);
>
> Yes, double can't represent the fractions exactly, but if we're
> concerned about that, we should test the difference is less than
> epsilon, or simply use representable values.
>
> > diff --git a/tests/unit/test-qobject-output-visitor.c
> > b/tests/unit/test-qobject-output-visitor.c
> > index 407ab9ed505a..ae05a726f775 100644
> > --- a/tests/unit/test-qobject-output-visitor.c
> > +++ b/tests/unit/test-qobject-output-visitor.c
> > @@ -571,7 +571,7 @@ static void
> > test_visitor_out_list_struct(TestOutputVisitorData *data,
> > i = 0;
> > QLIST_FOREACH_ENTRY(qlist, e) {
> > QNum *qvalue = qobject_to(QNum, qlist_entry_obj(e));
> > - char expected[32], actual[32];
> > + char expected[318], actual[318];
> >
> > g_assert(qvalue);
> > sprintf(expected, "%.6f", (double)i / 3);
>
> Likewise.
>
With regards,
Daniel
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