avutil/tests/dict: Explicitly test av_dict_iterate()

This commit tests it in a way that automatically checks
that using av_dict_iterate() is equivalent to using
av_dict_get() with key "" and AV_DICT_IGNORE_SUFFIX.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavutil/tests/dict.c

@@ -20,10 +20,30 @@
 
 #include "libavutil/dict.c"
 
+static const AVDictionaryEntry *dict_iterate(const AVDictionary *m,
+                                             const AVDictionaryEntry *prev)
+{
+    const AVDictionaryEntry *dict_get = av_dict_get(m, "", prev, AV_DICT_IGNORE_SUFFIX);
+    const AVDictionaryEntry *dict_iterate = av_dict_iterate(m, prev);
+
+    if (dict_get != dict_iterate) {
+#define GET(entry, mem) ((entry) ? (entry)->mem : "N/A")
+        printf("Iterating with av_dict_iterate() yields a different result "
+               "than iterating with av_dict_get() and AV_DICT_IGNORE_SUFFIX "
+               "(prev: %p, key %s; av_dict_iterate() %p, key %s, value %s; "
+               "av_dict_get() %p, key %s, value %s)\n",
+               prev, GET(prev, key),
+               dict_iterate, GET(dict_iterate, key), GET(dict_iterate, value),
+               dict_get, GET(dict_get, key), GET(dict_get, value));
+#undef GET
+    }
+    return dict_iterate;
+}
+
 static void print_dict(const AVDictionary *m)
 {
-    AVDictionaryEntry *t = NULL;
+    const AVDictionaryEntry *t = NULL;
-    while ((t = av_dict_get(m, "", t, AV_DICT_IGNORE_SUFFIX)))
+    while ((t = dict_iterate(m, t)))
         printf("%s %s   ", t->key, t->value);
     printf("\n");
 }
@@ -94,7 +114,7 @@ int main(void)
     if (av_dict_get(dict, NULL, NULL, 0))
         printf("av_dict_get() does not correctly handle NULL key.\n");
     e = NULL;
-    while ((e = av_dict_get(dict, "", e, AV_DICT_IGNORE_SUFFIX)))
+    while ((e = dict_iterate(dict, e)))
         printf("%s %s\n", e->key, e->value);
     av_dict_free(&dict);
 
@@ -106,7 +126,7 @@ int main(void)
         printf("av_dict_set does not correctly handle NULL key\n");
 
     e = NULL;
-    while ((e = av_dict_get(dict, "", e, AV_DICT_IGNORE_SUFFIX)))
+    while ((e = dict_iterate(dict, e)))
         printf("'%s' '%s'\n", e->key, e->value);
     av_dict_free(&dict);
 
@@ -122,7 +142,7 @@ int main(void)
     av_dict_set_int(&dict, "12", 1, 0);
     av_dict_set_int(&dict, "12", 2, AV_DICT_APPEND);
     e = NULL;
-    while ((e = av_dict_get(dict, "", e, AV_DICT_IGNORE_SUFFIX)))
+    while ((e = dict_iterate(dict, e)))
         printf("%s %s\n", e->key, e->value);
     av_dict_free(&dict);