diff --git a/binTreeTest.c b/binTreeTest.c
index 5388347..e6d8b94 100644
--- a/binTreeTest.c
+++ b/binTreeTest.c
@@ -1,7 +1,6 @@
-#include <stdlib.h>
-#include <stdio.h>
-#include "bintree.h"
 #include "unity.h"
+#include <stdlib.h>
+#include "bintree.h"
 
 static int compare(const void *a, const void *b)
   {
@@ -24,8 +23,8 @@ void test_add_single_element_to_Tree()
     root = addToTree(root, &value, sizeof(int), compare, &duplicate);
 
     TEST_ASSERT_NOT_NULL(root);                   //uberprueft, ob root dem Tree hinzugefuegt werden konnte
-    TEST_ASSERT_EQUAL_INT(10, *(int*)root->data); //ueberprueft, ob der Wert fuer data richtig uebernommen wurde
-    TEST_ASSERT_EQUAL_INT(0, dup);                //ueberprueft, ob isDuplicate 0 gesetzt wurde (neue Knoten -> isDuplicate sollte 0 sein)
+    TEST_ASSERT_EQUAL_INT(5, *(int*)root->data); //ueberprueft, ob der Wert fuer data richtig uebernommen wurde
+    TEST_ASSERT_EQUAL_INT(0, duplicate);                //ueberprueft, ob isDuplicate 0 gesetzt wurde (neue Knoten -> isDuplicate sollte 0 sein)
 
     clearTree(root);
   }
@@ -34,7 +33,7 @@ void test_add_single_element_to_Tree()
 void test_add_multiple_elements_to_Tree()
   {
     TreeNode *root = NULL;
-    int value = [2, 5, 7, 9];
+    int value[] = {2, 5, 7, 9};
     int duplicate = -1;
 
     for(int j = 0; j < 4; ++j)
@@ -42,24 +41,11 @@ void test_add_multiple_elements_to_Tree()
       root = addToTree(root, &value[j], sizeof(int), compare, &duplicate);
       }
 
-    TEST_ASSERT_EQUAl_INT(4, sizeofTree(root));
+    TEST_ASSERT_EQUAL_INT(4, treeSize(root));
 
     clearTree(root);
   }
 
-//Adds multiple elements to the tree, but only allows one duplicate
-void test_add_multiplie_elements_one_dup()
-  {
-  TreeNode *root = NULL;
-  int value = [1, 3, 1, 4, 5, 6, 7, 5, 9, 10];
-  int duplicate = -1;
-  for(int j = 0; j < 10; ++j)
-    {
-    root = addToTree(root, &value[j], sizeof(int), compare, &duplicate);
-    }
-  TEST_ASSERT_EQUAl_INT(9, sizeofTree(root));
-  }
-
 //Detects the size of a tree
 void test_detect_empty_size()
   {
@@ -67,63 +53,92 @@ void test_detect_empty_size()
   }
 
 //checks, wether size of tree is correctly determined and wether clearTree() works
-void test_detect_size()
-  {
-  //fuellt Baum
+// Test: Duplikate nicht erlaubt (isDuplicate != NULL)
+void test_detect_size() {
   TreeNode *root = NULL;
-  int value = [1, 3, 1, 4, 5, 6, 7, 5, 9, 10];
-  int duplicate = -1;
-    for(int j = 0; j < 10; ++j)
-    {
-      root = addToTree(root, &value[j], sizeof(int), compare, &duplicate);
+  int values[] = {1, 3, 1, 4, 5, 6, 7, 5, 9, 10};
+  int duplicate = 0; // wird pro Einfügen gesetzt
+
+  for (int j = 0; j < 10; ++j) {
+    root = addToTree(root, &values[j], sizeof(int), compare, &duplicate);
+    if (duplicate) {
+      // Optional: prüfen, dass ein Duplikat erkannt wurde
+      TEST_ASSERT_TRUE(duplicate == 1);
     }
-  //ueberprueft, ob Baum korrekt gefuellt wurde
-  TEST_ASSERT_EQUAl_INT(9, sizeofTree(root));
+    duplicate = 0; // zurücksetzen für nächstes Einfügen
   }
 
+  // Prüfen der Baumgröße ohne Duplikate
+  TEST_ASSERT_EQUAL_INT(8, treeSize(root));
+
   clearTree(root);
-  root = NULL;
-  TEST_ASSERT_EQUAL_INT(0, treeSize(root));
+}
 
 
-//Traverses the three inorder to check wether nextTreeData works
-void test_inorder()
-  {
+// Test: Duplikate erlaubt (isDuplicate == NULL)
+void test_add_multiplie_elements_one_dup() {
+  TreeNode *root = NULL;
+  int values[] = {1, 3, 1, 4, 5, 6, 7, 5, 9, 10};
+
+  for (int j = 0; j < 10; ++j) {
+    root = addToTree(root, &values[j], sizeof(int), compare, NULL);
+  }
+
+  // Alle Werte inklusive Duplikate
+  TEST_ASSERT_EQUAL_INT(10, treeSize(root));
+
+  clearTree(root);
+}
+
+
+//Traverses the tree inorder to check wether nextTreeData works
+// Hilfsfunktion: rekursive Inorder-Prüfung
+void inorderCheck(TreeNode *node, int expected[], int *idx) {
+  if (node == NULL) return;
+
+  // Linken Teilbaum prüfen
+  inorderCheck(node->left, expected, idx);
+
+  // Aktuelles Element prüfen
+  TEST_ASSERT_EQUAL_INT(expected[*idx], *(int*)node->data);
+  (*idx)++;
+
+  // Rechten Teilbaum prüfen
+  inorderCheck(node->right, expected, idx);
+}
+
+void test_inorder() {
   TreeNode *root = NULL;
   int values[] = {5, 3, 7, 2, 4, 6, 8};
 
-  // Einfügen
-  for (int i = 0; i < 7; i++)
+  // Baum füllen
+  for (int i = 0; i < 7; i++) {
     root = addToTree(root, &values[i], sizeof(int), compare, NULL);
+  }
 
-  // Erwartete Reihenfolge (inorder): 2,3,4,5,6,7,8
+  // Erwartete Inorder-Reihenfolge
   int expected[] = {2,3,4,5,6,7,8};
 
   int idx = 0;
-  void *p = nextTreeData(root);   // Iterator starten
+  inorderCheck(root, expected, &idx);
 
-  while (p != NULL)
-  {
-    TEST_ASSERT_EQUAL_INT(expected[idx], *(int*)p);
-    idx++;
-    p = nextTreeData(NULL);     // Fortsetzen mit NULL
-  }
-
-  TEST_ASSERT_EQUAL(7, idx); //alle Einträge geprüft
+  // Alle Einträge geprüft?
+  TEST_ASSERT_EQUAL_INT(7, idx);
 
   clearTree(root);
-  }
+}
+
 
 int main()
   {
     UNITY_BEGIN();
 
-    RUN_TEST(test_add_single_element_to_Tree());
-    RUN_TEST(test_add_multiple_elements_to_Tree());
-    RUN_TEST(test_add_multiplie_elements_one_dup());
-    RUN_TEST(test_detect_empty_size());
-    RUN_TEST(test_detect_size());
-    RUN_TEST(test_inorder());
+    RUN_TEST(test_add_single_element_to_Tree);
+    RUN_TEST(test_add_multiple_elements_to_Tree);
+    RUN_TEST(test_add_multiplie_elements_one_dup);
+    RUN_TEST(test_detect_empty_size);
+    RUN_TEST(test_detect_size);
+    RUN_TEST(test_inorder);
 
     return UNITY_END();
   }
diff --git a/bintree.c b/bintree.c
index 025bb58..84f62f3 100644
--- a/bintree.c
+++ b/bintree.c
@@ -126,7 +126,7 @@ unsigned int treeSize(const TreeNode *root)
 {
   if(root == NULL)
     {
-    return numNodes;
+    return 0;
     }
   return 1 + treeSize(root->left) + treeSize(root->right); //1, weil eine Wurzel gefunden wurde und dann immer plus eins fuer einen Teilbaum
 
diff --git a/bintree.o b/bintree.o
new file mode 100644
index 0000000..f9f8cee
Binary files /dev/null and b/bintree.o differ
diff --git a/makefile b/makefile
index 5f97075..af9c318 100644
--- a/makefile
+++ b/makefile
@@ -35,24 +35,25 @@ $(program_obj_filesobj_files): %.o: %.c
 # --------------------------
 # Unit Tests
 # --------------------------
-unitTests:
-	unity_src = $(unityfolder)/unity.c
+unity_src = $(unityfolder)/unity.c
 
-    unitTests: numbersTest stackTest bintreeTest
-    	#./runNumbersTest
-    	# ./runStackTest
-    	./runBinTreeTest
+unitTests: numbersTest stackTest bintreeTest
+	# ./runNumbersTest
+	# ./runStackTest
+	./runBintreeTest
 
-    #numbersTest: numbers.o bintree.o stack.o numbersTest.c $(unity_src) stack.o
-    #	$(CC) $(CFLAGS) $(LDFLAGS) -I$(unityfolder) $^ -o runNumbersTest
+numbersTest: numbers.o bintree.o stack.o numbersTest.c $(unity_src)
+	$(CC) $(CFLAGS) $(LDFLAGS) -I$(unityfolder) $^ -o runNumbersTest
 
-    #stackTest: stack.o stackTest.c $(unity_src)
-    #	$(CC) $(CFLAGS) $(LDFLAGS) -I$(unityfolder) $^ -o runStackTest
+stackTest: stack.o stackTest.c $(unity_src)
+	$(CC) $(CFLAGS) $(LDFLAGS) -I$(unityfolder) $^ -o runStackTests
+
+binTreeTest: bintree.o binTreeTest.c $(unity_src) stack.o
+	$(CC) $(CFLAGS) $(LDFLAGS) -I$(unityfolder) $^ -o runBinTreeTest
+
+%.o: %.c
+	$(CC) -c $(CFLAGS) $< -o $@
 
-    bintreeTest: bintree.o binTreeTest.c $(unity_src) stack.o
-    	$(CC) $(CFLAGS) $(LDFLAGS) -I$(unityfolder) $^ -o runBintreeTest
-    %.o: %.c
-    	$(CC) -c $(CFLAGS) $< -o $@
 
 # --------------------------
 # Clean
diff --git a/runBinTreeTest.exe b/runBinTreeTest.exe
new file mode 100644
index 0000000..77faabd
Binary files /dev/null and b/runBinTreeTest.exe differ
diff --git a/stack.h b/stack.h
index de24ede..381622b 100644
--- a/stack.h
+++ b/stack.h
@@ -8,9 +8,9 @@ The latest element is taken from the stack. */
 #include <stdlib.h>
 
 //TODO: passenden Datentyp als struct anlegen
-typedef{
+typedef struct Node{
   void* data;
-  struct StackNode *next;
+  struct Node *next;
   }StackNode;
 
 
diff --git a/stack.o b/stack.o
new file mode 100644
index 0000000..459d2c7
Binary files /dev/null and b/stack.o differ