diff --git a/test_numbers.c b/test_numbers.c
index e69de29..28a3ebe 100644
--- a/test_numbers.c
+++ b/test_numbers.c
@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "numbers.h"
+
+int main() {
+    printf("===== TEST NUMBERS =====\n");
+
+    unsigned int len = 20;
+    unsigned int *arr = createNumbers(len);
+
+    if (arr == NULL) {
+        printf("FAIL: createNumbers returned NULL\n");
+        return 1;
+    }
+
+    // Check length: should contain len numbers
+    printf("PASS: createNumbers != NULL\n");
+
+    // Count duplicates — exactly one number must appear twice
+    int countDuplicate = 0;
+
+    for (unsigned int i = 0; i < len; i++) {
+        for (unsigned int j = i + 1; j < len; j++) {
+            if (arr[i] == arr[j]) {
+                countDuplicate++;
+            }
+        }
+    }
+
+    if (countDuplicate != 1) {
+        printf("FAIL: Array must contain exactly one duplicate, found %d\n", countDuplicate);
+        free(arr);
+        return 1;
+    }
+    printf("PASS: exactly one duplicate\n");
+
+    unsigned int found = getDuplicate(arr, len);
+    printf("Duplicate found by getDuplicate(): %u\n", found);
+
+    if (found == 0) {
+        printf("FAIL: getDuplicate returned 0\n");
+        free(arr);
+        return 1;
+    }
+
+    printf("PASS: getDuplicate\n");
+
+    free(arr);
+    printf("PASS: free array\n");
+
+    printf("ALL NUMBERS TESTS PASSED\n");
+    return 0;
+}
diff --git a/test_numbers.exe b/test_numbers.exe
new file mode 100644
index 0000000..2782979
Binary files /dev/null and b/test_numbers.exe differ
diff --git a/test_stack.c b/test_stack.c
index e69de29..8ea2c5a 100644
--- a/test_stack.c
+++ b/test_stack.c
@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "stack.h"
+
+int main() {
+    printf("===== TEST STACK =====\n");
+
+    StackNode *s = NULL;
+
+    // Test push
+    int a = 10, b = 20, c = 30;
+    s = push(s, &a);
+    s = push(s, &b);
+    s = push(s, &c);
+
+    if (*(int*)top(s) != 30) {
+        printf("FAIL: top() should return 30\n");
+        return 1;
+    }
+    printf("PASS: push + top\n");
+
+    // Test pop
+    s = pop(s);
+    if (*(int*)top(s) != 20) {
+        printf("FAIL: pop() should remove 30\n");
+        return 1;
+    }
+    printf("PASS: pop\n");
+
+    // Clear
+    clearStack(s);
+    printf("PASS: clearStack (no crash)\n");
+
+    printf("ALL STACK TESTS PASSED\n");
+    return 0;
+}
diff --git a/test_stack.exe b/test_stack.exe
new file mode 100644
index 0000000..88520a5
Binary files /dev/null and b/test_stack.exe differ