diff -r 8bfccb342895 -r 9a72258446cd tests/test_list.c
--- a/tests/test_list.c	Sat Oct 11 11:55:46 2025 +0200
+++ b/tests/test_list.c	Sat Oct 11 15:42:48 2025 +0200
@@ -36,6 +36,7 @@
 
 #include <stdarg.h>
 #include <errno.h>
+#include <unistd.h>
 
 CX_TEST(test_array_add) {
     CX_ARRAY_DECLARE(int, arr);
@@ -2456,6 +2457,73 @@
     cxListFree(list);
 }
 
+CX_TEST(test_list_use_insert_unique_to_remove_duplicates) {
+    CxList *linked_list = cxLinkedListCreate(cxDefaultAllocator, cx_cmp_int, sizeof(int));
+    CxList *array_list = cxArrayListCreate(cxDefaultAllocator, cx_cmp_int, sizeof(int), 8);
+    CxList *defaulted_list = cxArrayListCreate(cxDefaultAllocator, cx_cmp_int, sizeof(int), 8);
+    do_set_default_class_funcs(defaulted_list);
+    int test_array[23] = {
+        120, -13, 100, -90, 13, -56, 74, 20, 28, 80, 18, -56, 130, 12, 15, 0, 39, 100, 0, 29, 28, 85, 20
+    };
+    int test_array_unique[18] = {
+        -90, -56, -13, 0, 12, 13, 15, 18, 20, 28, 29, 39, 74, 80, 85, 100, 120, 130
+    };
+    CX_TEST_DO {
+        qsort(test_array, 23, sizeof(int), cx_cmp_int);
+        cxListInsertUniqueArray(linked_list, test_array, 23);
+        cxListInsertUniqueArray(array_list, test_array, 23);
+        cxListInsertUniqueArray(defaulted_list, test_array, 23);
+        CX_TEST_ASSERT(cxListSize(linked_list) == 18);
+        CX_TEST_ASSERT(cxListSize(array_list) == 18);
+        CX_TEST_ASSERT(cxListSize(defaulted_list) == 18);
+        for (unsigned i = 0; i < 18; i++) {
+            CX_TEST_ASSERT(*(int *) cxListAt(linked_list, i) == test_array_unique[i]);
+            CX_TEST_ASSERT(*(int *) cxListAt(array_list, i) == test_array_unique[i]);
+            CX_TEST_ASSERT(*(int *) cxListAt(defaulted_list, i) == test_array_unique[i]);
+        }
+    }
+    cxListFree(defaulted_list);
+    cxListFree(linked_list);
+    cxListFree(array_list);
+}
+
+CX_TEST(test_list_use_insert_unique_with_duplicates_in_source) {
+    CxList *linked_list = cxLinkedListCreate(cxDefaultAllocator, cx_cmp_int, sizeof(int));
+    CxList *array_list = cxArrayListCreate(cxDefaultAllocator, cx_cmp_int, sizeof(int), 8);
+    CxList *defaulted_list = cxArrayListCreate(cxDefaultAllocator, cx_cmp_int, sizeof(int), 8);
+    do_set_default_class_funcs(defaulted_list);
+    int pre_filled[10] = {-13, 5, 18, 30, 40, 45, 50, 80, 85, 110};
+    cxListInsertSortedArray(linked_list, pre_filled, 10);
+    cxListInsertSortedArray(array_list, pre_filled, 10);
+    cxListInsertSortedArray(defaulted_list, pre_filled, 10);
+    int test_array[23] = {
+        120, -13, 100, -90, 13, -56, 74, 20, 28, 80, 18, -56, 130, 12, 15, 0, 39, 100, 0, 29, 28, 85, 20
+    };
+    int test_array_unique[24] = {
+        -90, -56, -13, 0, 5, 12, 13, 15, 18, 20, 28, 29, 30, 39, 40, 45, 50, 74, 80, 85, 100, 110, 120, 130
+    };
+    CX_TEST_DO {
+        qsort(test_array, 23, sizeof(int), cx_cmp_int);
+        cxListInsertUniqueArray(linked_list, test_array, 23);
+        cxListInsertUniqueArray(array_list, test_array, 23);
+        cxListInsertUniqueArray(defaulted_list, test_array, 23);
+        CX_TEST_ASSERT(cxListSize(linked_list) == 24);
+        CX_TEST_ASSERT(cxListSize(array_list) == 24);
+        CX_TEST_ASSERT(cxListSize(defaulted_list) == 24);
+        for (unsigned i = 0; i < 24; i++) {
+            CX_TEST_ASSERT(*(int *) cxListAt(linked_list, i) == test_array_unique[i]);
+            CX_TEST_ASSERT(*(int *) cxListAt(array_list, i) == test_array_unique[i]);
+            CX_TEST_ASSERT(*(int *) cxListAt(defaulted_list, i) == test_array_unique[i]);
+        }
+        CX_TEST_ASSERT(*(int*)cxListLast(linked_list) == 130);
+        CX_TEST_ASSERT(*(int*)cxListLast(array_list) == 130);
+        CX_TEST_ASSERT(*(int*)cxListLast(defaulted_list) == 130);
+    }
+    cxListFree(defaulted_list);
+    cxListFree(linked_list);
+    cxListFree(array_list);
+}
+
 CxTestSuite *cx_test_suite_array_list(void) {
     CxTestSuite *suite = cx_test_suite_new("array_list");
 
@@ -2747,6 +2815,8 @@
     CxTestSuite *suite = cx_test_suite_new("list corner cases");
 
     cx_test_register(suite, test_list_pointer_list_supports_null);
+    cx_test_register(suite, test_list_use_insert_unique_with_duplicates_in_source);
+    cx_test_register(suite, test_list_use_insert_unique_to_remove_duplicates);
 
     return suite;
 }