diff -r 3270ea9e41ef -r 2615317311b7 tests/test_tree.c
--- a/tests/test_tree.c	Thu Mar 14 22:07:19 2024 +0100
+++ b/tests/test_tree.c	Wed Mar 20 23:31:41 2024 +0100
@@ -286,6 +286,14 @@
     tree_node cc = {0};
     tree_node cba = {0};
 
+    tree_node* expected_order[] = {
+            &root,
+            &c, &cc,&cb, &cba,&ca,
+            &b, &ba,
+            &a, &ab, &aa,
+    };
+    tree_node* actual_order[16]; // reserve more space in case s.t. goes wrong
+
     cx_tree_link(&root, &a, tree_node_layout);
     cx_tree_link(&root, &b, tree_node_layout);
     cx_tree_link(&root, &c, tree_node_layout);
@@ -302,6 +310,7 @@
         cx_foreach(tree_node*, node, iter) {
             CX_TEST_ASSERT(node->data == 0);
             node->data++;
+            actual_order[chk] = node;
             chk++;
             CX_TEST_ASSERT(node == iter.node);
             CX_TEST_ASSERT(!iter.exiting);
@@ -317,18 +326,11 @@
         }
         CX_TEST_ASSERT(iter.counter == 11);
         CX_TEST_ASSERT(chk == 11);
+        for (unsigned i = 0 ; i < chk ; i++) {
+            CX_TEST_ASSERT(actual_order[i] == expected_order[i]);
+            CX_TEST_ASSERT(actual_order[i]->data == 1);
+        }
         CX_TEST_ASSERT(iter.stack == NULL);
-        CX_TEST_ASSERT(root.data == 1);
-        CX_TEST_ASSERT(a.data == 1);
-        CX_TEST_ASSERT(b.data == 1);
-        CX_TEST_ASSERT(c.data == 1);
-        CX_TEST_ASSERT(aa.data == 1);
-        CX_TEST_ASSERT(ab.data == 1);
-        CX_TEST_ASSERT(ba.data == 1);
-        CX_TEST_ASSERT(ca.data == 1);
-        CX_TEST_ASSERT(cb.data == 1);
-        CX_TEST_ASSERT(cc.data == 1);
-        CX_TEST_ASSERT(cba.data == 1);
     }
 }
 
@@ -507,6 +509,120 @@
     cx_testing_allocator_destroy(&talloc);
 }
 
+CX_TEST(test_tree_visitor) {
+    tree_node root = {0};
+    tree_node a = {0};
+    tree_node b = {0};
+    tree_node c = {0};
+    tree_node aa = {0};
+    tree_node ab = {0};
+    tree_node ba = {0};
+    tree_node ca = {0};
+    tree_node cb = {0};
+    tree_node cc = {0};
+    tree_node cba = {0};
+
+    tree_node* expected_order[] = {
+            &root,
+            &c, &b, &a,
+            &cc, &cb, &ca, &ba, &ab, &aa,
+            &cba
+    };
+    tree_node* actual_order[16]; // reserve more space in case s.t. goes wrong
+
+    cx_tree_link(&root, &a, tree_node_layout);
+    cx_tree_link(&root, &b, tree_node_layout);
+    cx_tree_link(&root, &c, tree_node_layout);
+    cx_tree_link(&a, &aa, tree_node_layout);
+    cx_tree_link(&a, &ab, tree_node_layout);
+    cx_tree_link(&b, &ba, tree_node_layout);
+    cx_tree_link(&c, &ca, tree_node_layout);
+    cx_tree_link(&c, &cb, tree_node_layout);
+    cx_tree_link(&c, &cc, tree_node_layout);
+    cx_tree_link(&cb, &cba, tree_node_layout);
+    CX_TEST_DO {
+        CxTreeVisitor iter = cx_tree_visitor(&root, tree_child_list);
+        unsigned chk = 0;
+        cx_foreach(tree_node*, node, iter) {
+            CX_TEST_ASSERT(node->data == 0);
+            node->data++;
+            actual_order[chk] = node;
+            chk++;
+            CX_TEST_ASSERT(node == iter.node);
+            if (node == &root) {
+                CX_TEST_ASSERT(iter.depth == 1);
+            } else if (node == &a || node == &b || node == &c) {
+                CX_TEST_ASSERT(iter.depth == 2);
+            } else if (node == &cba) {
+                CX_TEST_ASSERT(iter.depth == 4);
+            } else {
+                CX_TEST_ASSERT(iter.depth == 3);
+            }
+        }
+        CX_TEST_ASSERT(iter.counter == 11);
+        CX_TEST_ASSERT(chk == 11);
+        for (unsigned i = 0 ; i < chk ; i++) {
+            CX_TEST_ASSERT(actual_order[i] == expected_order[i]);
+            CX_TEST_ASSERT(actual_order[i]->data == 1);
+        }
+        CX_TEST_ASSERT(iter.queue_next == NULL);
+        CX_TEST_ASSERT(iter.queue_last == NULL);
+    }
+}
+
+CX_TEST(test_tree_visitor_no_children) {
+    tree_node root = {0};
+
+    CX_TEST_DO {
+        CxTreeVisitor iter = cx_tree_visitor(&root, tree_child_list);
+        unsigned chk = 0;
+        cx_foreach(tree_node*, node, iter) {
+            CX_TEST_ASSERT(node == iter.node);
+            chk++;
+        }
+        CX_TEST_ASSERT(iter.counter == 1);
+        CX_TEST_ASSERT(chk == 1);
+        CX_TEST_ASSERT(iter.queue_next == NULL);
+        CX_TEST_ASSERT(iter.queue_last == NULL);
+    }
+}
+
+CX_TEST(test_tree_visitor_no_branching) {
+    tree_node root = {0};
+    tree_node a = {0};
+    tree_node b = {0};
+    tree_node c = {0};
+
+    tree_node* expected_order[] = {
+            &root, &a, &b, &c
+    };
+    tree_node* actual_order[4];
+
+    cx_tree_link(&root, &a, tree_node_layout);
+    cx_tree_link(&a, &b, tree_node_layout);
+    cx_tree_link(&b, &c, tree_node_layout);
+
+    CX_TEST_DO {
+        CxTreeVisitor iter = cx_tree_visitor(&root, tree_child_list);
+        unsigned chk = 0;
+        cx_foreach(tree_node*, node, iter) {
+            CX_TEST_ASSERT(node == iter.node);
+            CX_TEST_ASSERT(node->data == 0);
+            node->data++;
+            actual_order[chk] = node;
+            chk++;
+        }
+        CX_TEST_ASSERT(iter.counter == 4);
+        CX_TEST_ASSERT(chk == 4);
+        CX_TEST_ASSERT(iter.queue_next == NULL);
+        CX_TEST_ASSERT(iter.queue_last == NULL);
+        for (unsigned i = 0 ; i < chk ; i++) {
+            CX_TEST_ASSERT(actual_order[i] == expected_order[i]);
+            CX_TEST_ASSERT(actual_order[i]->data == 1);
+        }
+    }
+}
+
 CxTestSuite *cx_test_suite_tree_low_level(void) {
     CxTestSuite *suite = cx_test_suite_new("tree (low level)");
 
@@ -520,6 +636,9 @@
     cx_test_register(suite, test_tree_iterator_basic_enter_and_exit);
     cx_test_register(suite, test_tree_iterator_xml);
     cx_test_register(suite, test_tree_iterator_free_nodes);
+    cx_test_register(suite, test_tree_visitor);
+    cx_test_register(suite, test_tree_visitor_no_children);
+    cx_test_register(suite, test_tree_visitor_no_branching);
 
     return suite;
 }