diff --git a/test_bintree.c b/test_bintree.c
index 3ca280d..2f2ba5e 100644
--- a/test_bintree.c
+++ b/test_bintree.c
@@ -1,39 +1,145 @@
 #include "unity.h"
 #include "bintree.h"
-#include "string.h"
+#include <string.h>
+#include <stdio.h>
+
+static int compareInt(const void *a, const void *b)
+{
+    int x = *(const int *)a;
+    int y = *(const int *)b;
+    return (x > y) - (x < y);
+}
 
 void setUp(void)
 {
-    // set stuff up here
 }
 
 void tearDown(void)
 {
-    // set stuff up here
 }
 
-// this adds some strings and checks if they are returned in the right order
-void test_insert_and_retrieve(void)
+/* ============================================================
+   TEST 1 — Strings einfügen + korrekte Reihenfolge prüfen
+   ============================================================ */
+
+void test_insert_and_retrieve_strings(void)
 {
     char *data1 = "a_this";
     char *data2 = "b_is";
     char *data3 = "c_testdata";
 
-    TreeNode *root = addToTree(NULL, data1, strlen(data1) + 1, (CompareFctType)&strcmp, NULL);
-    addToTree(root, data2, strlen(data2) + 1, (CompareFctType)&strcmp, NULL);
-    addToTree(root, data3, strlen(data3) + 1, (CompareFctType)&strcmp, NULL);
+    TreeNode *root = addToTree(NULL, data1, strlen(data1) + 1, (CompareFctType)strcmp, NULL);
+    addToTree(root, data2, strlen(data2) + 1, (CompareFctType)strcmp, NULL);
+    addToTree(root, data3, strlen(data3) + 1, (CompareFctType)strcmp, NULL);
 
-    TEST_ASSERT_EQUAL_STRING(data1, (char *)nextTreeData(root));
-    TEST_ASSERT_EQUAL_STRING(data2, (char *)nextTreeData(NULL));
-    TEST_ASSERT_EQUAL_STRING(data3, (char *)nextTreeData(NULL));
+    TEST_ASSERT_EQUAL_STRING(data1, nextTreeData(root));
+    TEST_ASSERT_EQUAL_STRING(data2, nextTreeData(NULL));
+    TEST_ASSERT_EQUAL_STRING(data3, nextTreeData(NULL));
+    TEST_ASSERT_EQUAL_PTR(NULL, nextTreeData(NULL)); // Ende
 
     clearTree(root);
 }
 
+/* ============================================================
+   TEST 2 — Integer einfügen + Traversierung
+   ============================================================ */
+
+void test_insert_and_retrieve_ints(void)
+{
+    int a = 2, b = 1, c = 3;
+
+    TreeNode *root = NULL;
+    root = addToTree(root, &a, sizeof(int), compareInt, NULL);
+    addToTree(root, &b, sizeof(int), compareInt, NULL);
+    addToTree(root, &c, sizeof(int), compareInt, NULL);
+
+    int *v1 = nextTreeData(root);
+    int *v2 = nextTreeData(NULL);
+    int *v3 = nextTreeData(NULL);
+    int *v4 = nextTreeData(NULL);
+
+    TEST_ASSERT_EQUAL_INT(1, *v1);
+    TEST_ASSERT_EQUAL_INT(2, *v2);
+    TEST_ASSERT_EQUAL_INT(3, *v3);
+    TEST_ASSERT_NULL(v4);
+
+    clearTree(root);
+}
+
+/* ============================================================
+   TEST 3 — treeSize korrekt?
+   ============================================================ */
+
+void test_tree_size(void)
+{
+    TreeNode *root = NULL;
+
+    TEST_ASSERT_EQUAL_UINT(0, treeSize(root));
+
+    int x1 = 10, x2 = 5, x3 = 15;
+    root = addToTree(root, &x1, sizeof(int), compareInt, NULL);
+    addToTree(root, &x2, sizeof(int), compareInt, NULL);
+    addToTree(root, &x3, sizeof(int), compareInt, NULL);
+
+    TEST_ASSERT_EQUAL_UINT(3, treeSize(root));
+
+    clearTree(root);
+}
+
+/* ============================================================
+   TEST 4 — Duplikaterkennung
+   ============================================================ */
+
+void test_duplicate_detection(void)
+{
+    int x = 42;
+    int dupFlag = -1;
+
+    TreeNode *root = addToTree(NULL, &x, sizeof(int), compareInt, &dupFlag);
+    TEST_ASSERT_EQUAL_INT(0, dupFlag);
+
+    addToTree(root, &x, sizeof(int), compareInt, &dupFlag);
+    TEST_ASSERT_EQUAL_INT(1, dupFlag);
+
+    TEST_ASSERT_EQUAL_UINT(1, treeSize(root));
+
+    clearTree(root);
+}
+
+/* ============================================================
+   TEST 5 — Iterator nach clearTree → sollte NULL liefern
+   ============================================================ */
+
+void test_iterator_after_cleartree(void)
+{
+    int a = 5, b = 1, c = 9;
+
+    TreeNode *root = NULL;
+    root = addToTree(root, &a, sizeof(int), compareInt, NULL);
+    addToTree(root, &b, sizeof(int), compareInt, NULL);
+    addToTree(root, &c, sizeof(int), compareInt, NULL);
+
+    nextTreeData(root);
+
+    clearTree(root);
+
+    TEST_ASSERT_NULL(nextTreeData(NULL));
+    TEST_ASSERT_NULL(nextTreeData(NULL));
+}
+
 int main(void)
 {
-    printf("============================\nBintree tests\n============================\n");
+    printf("============================\n");
+    printf("Bintree tests\n");
+    printf("============================\n");
+
     UNITY_BEGIN();
-    RUN_TEST(test_insert_and_retrieve);
+
+    RUN_TEST(test_insert_and_retrieve_strings);
+    RUN_TEST(test_insert_and_retrieve_ints);
+    RUN_TEST(test_tree_size);
+    RUN_TEST(test_duplicate_detection);
+    RUN_TEST(test_iterator_after_cleartree);
+
     return UNITY_END();
-}
\ No newline at end of file
+}