diff -r eef025d82a34 -r 0d998f19d130 test/test_list.c
--- a/test/test_list.c	Thu Dec 23 15:20:50 2021 +0100
+++ b/test/test_list.c	Mon Dec 27 14:44:08 2021 +0100
@@ -35,6 +35,40 @@
     return left == right ? 0 : (left < right ? -1 : 1);
 }
 
+void test_linked_list_link_unlink(void) {
+    struct node {
+        void *next;
+        void *prev;
+    };
+    const ptrdiff_t loc_prev = offsetof(struct node, prev);
+    const ptrdiff_t loc_next = offsetof(struct node, next);
+
+    struct node a = {NULL, NULL}, b = {NULL, NULL};
+
+    cx_linked_list_link(&a, &b, loc_prev, loc_next);
+    CU_ASSERT_PTR_NULL(a.prev)
+    CU_ASSERT_PTR_EQUAL(a.next, &b)
+    CU_ASSERT_PTR_EQUAL(b.prev, &a)
+    CU_ASSERT_PTR_NULL(b.next)
+
+    cx_linked_list_unlink(&a, &b, loc_prev, loc_next);
+    CU_ASSERT_PTR_NULL(a.prev)
+    CU_ASSERT_PTR_NULL(a.next)
+    CU_ASSERT_PTR_NULL(b.prev)
+    CU_ASSERT_PTR_NULL(b.next)
+
+    struct node c = {NULL, NULL};
+    cx_linked_list_link(&b, &c, loc_prev, loc_next);
+    cx_linked_list_link(&a, &b, loc_prev, loc_next);
+    cx_linked_list_unlink(&b, &c, loc_prev, loc_next);
+    CU_ASSERT_PTR_NULL(a.prev)
+    CU_ASSERT_PTR_EQUAL(a.next, &b)
+    CU_ASSERT_PTR_EQUAL(b.prev, &a)
+    CU_ASSERT_PTR_NULL(b.next)
+    CU_ASSERT_PTR_NULL(c.prev)
+    CU_ASSERT_PTR_NULL(c.next)
+}
+
 void test_linked_list_at(void) {
     struct node {
         void *next;
@@ -224,6 +258,125 @@
     CU_ASSERT_PTR_NULL(nodes[0].prev)
 }
 
+void test_linked_list_insert(void) {
+    struct node {
+        void *prev;
+        void *next;
+    };
+    ptrdiff_t loc_prev = offsetof(struct node, prev);
+    ptrdiff_t loc_next = offsetof(struct node, next);
+
+    struct node nodes[4];
+    void *begin, *end;
+
+    // insert mid list
+    memset(nodes, 0, 4 * sizeof(struct node));
+    begin = &nodes[0];
+    end = &nodes[2];
+
+    cx_linked_list_link(&nodes[0], &nodes[1], loc_prev, loc_next);
+    cx_linked_list_link(&nodes[1], &nodes[2], loc_prev, loc_next);
+
+    cx_linked_list_insert(&begin, &end, loc_prev, loc_next, &nodes[1], &nodes[3]);
+    CU_ASSERT_PTR_EQUAL(begin, &nodes[0])
+    CU_ASSERT_PTR_EQUAL(end, &nodes[2])
+    CU_ASSERT_PTR_EQUAL(nodes[1].next, &nodes[3])
+    CU_ASSERT_PTR_EQUAL(nodes[2].prev, &nodes[3])
+    CU_ASSERT_PTR_EQUAL(nodes[3].prev, &nodes[1])
+    CU_ASSERT_PTR_EQUAL(nodes[3].next, &nodes[2])
+
+    // insert end
+    memset(nodes, 0, 4 * sizeof(struct node));
+    begin = &nodes[0];
+    end = &nodes[2];
+
+    cx_linked_list_link(&nodes[0], &nodes[1], loc_prev, loc_next);
+    cx_linked_list_link(&nodes[1], &nodes[2], loc_prev, loc_next);
+
+    cx_linked_list_insert(&begin, &end, loc_prev, loc_next, &nodes[2], &nodes[3]);
+    CU_ASSERT_PTR_EQUAL(begin, &nodes[0])
+    CU_ASSERT_PTR_EQUAL(end, &nodes[3])
+    CU_ASSERT_PTR_EQUAL(nodes[2].next, &nodes[3])
+    CU_ASSERT_PTR_EQUAL(nodes[3].prev, &nodes[2])
+    CU_ASSERT_PTR_NULL(nodes[3].next)
+
+    // insert begin
+    memset(nodes, 0, 4 * sizeof(struct node));
+    begin = &nodes[0];
+    end = &nodes[2];
+
+    cx_linked_list_link(&nodes[0], &nodes[1], loc_prev, loc_next);
+    cx_linked_list_link(&nodes[1], &nodes[2], loc_prev, loc_next);
+
+    cx_linked_list_insert(&begin, &end, loc_prev, loc_next, NULL, &nodes[3]);
+    CU_ASSERT_PTR_EQUAL(begin, &nodes[3])
+    CU_ASSERT_PTR_EQUAL(end, &nodes[2])
+    CU_ASSERT_PTR_EQUAL(nodes[0].prev, &nodes[3])
+    CU_ASSERT_PTR_NULL(nodes[3].prev)
+    CU_ASSERT_PTR_EQUAL(nodes[3].next, &nodes[0])
+}
+
+void test_linked_list_insert_chain(void) {
+    struct node {
+        void *prev;
+        void *next;
+    };
+    ptrdiff_t loc_prev = offsetof(struct node, prev);
+    ptrdiff_t loc_next = offsetof(struct node, next);
+
+    struct node nodes[5];
+    void *begin, *end;
+
+    // insert mid list
+    memset(nodes, 0, 5 * sizeof(struct node));
+    begin = &nodes[0];
+    end = &nodes[2];
+
+    cx_linked_list_link(&nodes[0], &nodes[1], loc_prev, loc_next);
+    cx_linked_list_link(&nodes[1], &nodes[2], loc_prev, loc_next);
+    cx_linked_list_link(&nodes[3], &nodes[4], loc_prev, loc_next);
+
+    cx_linked_list_insert_chain(&begin, &end, loc_prev, loc_next, &nodes[1], &nodes[3], NULL);
+    CU_ASSERT_PTR_EQUAL(begin, &nodes[0])
+    CU_ASSERT_PTR_EQUAL(end, &nodes[2])
+    CU_ASSERT_PTR_EQUAL(nodes[1].next, &nodes[3])
+    CU_ASSERT_PTR_EQUAL(nodes[2].prev, &nodes[4])
+    CU_ASSERT_PTR_EQUAL(nodes[3].prev, &nodes[1])
+    CU_ASSERT_PTR_EQUAL(nodes[4].next, &nodes[2])
+
+    // insert end
+    memset(nodes, 0, 5 * sizeof(struct node));
+    begin = &nodes[0];
+    end = &nodes[2];
+
+    cx_linked_list_link(&nodes[0], &nodes[1], loc_prev, loc_next);
+    cx_linked_list_link(&nodes[1], &nodes[2], loc_prev, loc_next);
+    cx_linked_list_link(&nodes[3], &nodes[4], loc_prev, loc_next);
+
+    cx_linked_list_insert_chain(&begin, &end, loc_prev, loc_next, &nodes[2], &nodes[3], NULL);
+    CU_ASSERT_PTR_EQUAL(begin, &nodes[0])
+    CU_ASSERT_PTR_EQUAL(end, &nodes[4])
+    CU_ASSERT_PTR_EQUAL(nodes[2].next, &nodes[3])
+    CU_ASSERT_PTR_EQUAL(nodes[3].prev, &nodes[2])
+    CU_ASSERT_PTR_NULL(nodes[4].next)
+
+    // insert begin
+    memset(nodes, 0, 5 * sizeof(struct node));
+    begin = &nodes[0];
+    end = &nodes[2];
+
+    cx_linked_list_link(&nodes[0], &nodes[1], loc_prev, loc_next);
+    cx_linked_list_link(&nodes[1], &nodes[2], loc_prev, loc_next);
+    cx_linked_list_link(&nodes[3], &nodes[4], loc_prev, loc_next);
+
+    cx_linked_list_insert_chain(&begin, &end, loc_prev, loc_next, NULL, &nodes[3], NULL);
+    CU_ASSERT_PTR_EQUAL(begin, &nodes[3])
+    CU_ASSERT_PTR_EQUAL(end, &nodes[2])
+    CU_ASSERT_PTR_EQUAL(nodes[0].prev, &nodes[4])
+    CU_ASSERT_PTR_NULL(nodes[3].prev)
+    CU_ASSERT_PTR_EQUAL(nodes[4].next, &nodes[0])
+}
+
 void test_linked_list_first(void) {
     struct node {
         int data;
@@ -873,9 +1026,12 @@
 
     suite = CU_add_suite("low level linked list", NULL, NULL);
 
+    cu_add_test(suite, test_linked_list_link_unlink);
     cu_add_test(suite, test_linked_list_at);
     cu_add_test(suite, test_linked_list_prepend);
     cu_add_test(suite, test_linked_list_add);
+    cu_add_test(suite, test_linked_list_insert);
+    cu_add_test(suite, test_linked_list_insert_chain);
     cu_add_test(suite, test_linked_list_first);
     cu_add_test(suite, test_linked_list_last);
     cu_add_test(suite, test_linked_list_prev);