testsuite: cover idset AUTOGROW flag

src/common/libidset/test/idset.c

@@ -424,6 +424,41 @@ void test_copy (void)
     idset_destroy (idset);
 }
 
+void test_autogrow (void)
+{
+    struct idset *idset;
+
+    idset = idset_create (1, 0);
+    ok (idset != NULL,
+        "idset_create size=1 flags=0 works");
+    ok (idset->T.M == 1,
+        "idset internal size is 1");
+    ok (idset_set (idset, 0) == 0,
+        "idset_set 0 works");
+    errno = 0;
+    ok (idset_set (idset, 1) < 0 && errno == EINVAL,
+        "idset_set 1 fails with EINVAL");
+    idset_destroy (idset);
+
+    idset = idset_create (1, IDSET_FLAG_AUTOGROW);
+    ok (idset != NULL,
+        "idset_create size=1 flags=AUTOGROW works");
+    ok (idset->T.M == 1,
+        "idset internal size is 1");
+    ok (idset_set (idset, 0) == 0,
+        "idset_set 0 works");
+    ok (idset_set (idset, 2) == 0,
+        "idset_set 2 works");
+    ok (idset->T.M > 1,
+        "idset internal size grew");
+    ok (   idset_test (idset, 0)
+        && !idset_test (idset, 1)
+        && idset_test (idset, 2)
+        && !idset_test (idset, 3),
+        "idset contains expected ids");
+    idset_destroy (idset);
+}
+
 int main (int argc, char *argv[])
 {
     plan (NO_PLAN);
@@ -438,6 +473,7 @@ int main (int argc, char *argv[])
     test_clear ();
     test_range_clear ();
     test_copy ();
+    test_autogrow ();
 
     done_testing ();
 }