list: add list_next and list_prev helpers.

[ccan] / ccan / list / test / run-list_prev-list_next.c

diff --git a/ccan/list/test/run-list_prev-list_next.c b/ccan/list/test/run-list_prev-list_next.c
new file mode 100644 (file)
index 0000000..85611d9
--- /dev/null
+++ b/ccan/list/test/run-list_prev-list_next.c
@@ -0,0 +1,50 @@
+#include <ccan/list/list.h>
+#include <ccan/tap/tap.h>
+#include <ccan/list/list.c>
+#include "helper.h"
+
+struct parent {
+       const char *name;
+       unsigned int num_children;
+       struct list_head children;
+};
+
+struct child {
+       const char *name;
+       struct list_node list;
+};
+
+int main(int argc, char *argv[])
+{
+       struct parent parent;
+       struct child c1, c2, c3;
+
+       plan_tests(12);
+       parent.num_children = 0;
+       list_head_init(&parent.children);
+
+       c1.name = "c1";
+       list_add(&parent.children, &c1.list);
+
+       ok1(list_next(&parent.children, &c1, list) == NULL);
+       ok1(list_prev(&parent.children, &c1, list) == NULL);
+
+       c2.name = "c2";
+       list_add_tail(&parent.children, &c2.list);
+
+       ok1(list_next(&parent.children, &c1, list) == &c2);
+       ok1(list_prev(&parent.children, &c1, list) == NULL);
+       ok1(list_next(&parent.children, &c2, list) == NULL);
+       ok1(list_prev(&parent.children, &c2, list) == &c1);
+
+       c3.name = "c3";
+       list_add_tail(&parent.children, &c3.list);
+
+       ok1(list_next(&parent.children, &c1, list) == &c2);
+       ok1(list_prev(&parent.children, &c1, list) == NULL);
+       ok1(list_next(&parent.children, &c2, list) == &c3);
+       ok1(list_prev(&parent.children, &c2, list) == &c1);
+       ok1(list_next(&parent.children, &c3, list) == NULL);
+       ok1(list_prev(&parent.children, &c3, list) == &c2);
+       return exit_status();
+}