diff --git a/I2_Dobble/makefile b/I2_Dobble/makefile
index f2acc1f..b60440c 100644
--- a/I2_Dobble/makefile
+++ b/I2_Dobble/makefile
@@ -36,11 +36,15 @@ $(program_obj_filesobj_files): %.o: %.c
 # --------------------------
 # Unit Tests
 # --------------------------
-unitTests: numbersTest
+unitTests: numbersTest stackTest
 	./runNumbersTest
+	./runStackTest
 
-numbersTest: numbers.o bintree.o numbersTest.o $($(unityfolder)/unity.c)
-	$(CC) $(FLAGS) $(LDFLAGS) $^ -o $@
+numbersTest: numbers.o bintree.o numbersTest.o $(unityfolder)/unity.c
+	$(CC) $(FLAGS) $(LDFLAGS) $^ -o runNumbersTest
+
+stackTest: stack.o stackTest.o $(unityfolder)/unity.c
+	$(CC) $(FLAGS) $(LDFLAGS) $^ -o runStackTest
 
 %.o: %.c
 	$(CC) -c $(FLAGS) $< -o $@
@@ -50,7 +54,7 @@ numbersTest: numbers.o bintree.o numbersTest.o $($(unityfolder)/unity.c)
 # --------------------------
 clean:
 ifeq ($(OS),Windows_NT)
-	del /f *.o doble runNumbersTest
+	del /f *.o doble runNumbersTest runStackTest
 else
-	rm -f *.o doble runNumbersTest
+	rm -f *.o doble runNumbersTest runStackTest
 endif
\ No newline at end of file
diff --git a/I2_Dobble/stack.c b/I2_Dobble/stack.c
index e3a90d4..2bc5825 100644
--- a/I2_Dobble/stack.c
+++ b/I2_Dobble/stack.c
@@ -1,7 +1,7 @@
 #include <stdlib.h>
 #include "stack.h"
 
-//TODO: grundlegende Stackfunktionen implementieren:
+//DONE: grundlegende Stackfunktionen implementieren:
 /*  * `push`: legt ein Element oben auf den Stack,
     * `pop`: entfernt das oberste Element,
     * `top`: liefert das oberste Element zurück,
@@ -10,24 +10,52 @@
 // Pushes data as pointer onto the stack.
 StackNode *push(StackNode *stack, void *data)
 {
-
+    //        ,-→ Wenn keine Daten angegeben wird die Liste unverändert zurückgegeben
+    if (data != NULL)
+    {
+        StackNode *newNode;
+        newNode = (StackNode *)malloc(sizeof(StackNode));
+        newNode->data = data;
+        
+        //         ,-→ bedeutet Liste war leer - das neue Element hat keinen Nachfolger (next = NULL)
+        if (stack == NULL) {
+            newNode->next = NULL;
+        } else {
+            newNode->next = stack;
+        }
+        stack = newNode;
+    }
+    
+    return stack;
 }
 
-// Deletes the top element of the stack (latest added element) and releases its memory. (Pointer to data has to be
-// freed by caller.)
+// Deletes the top element of the stack (latest added element) and releases its memory.
+// (Pointer to data has to be freed by caller.)
 StackNode *pop(StackNode *stack)
 {
-
+    if(stack != NULL)
+    {
+        StackNode *nextNode = stack->next;
+        free(stack);
+        stack = nextNode;
+    }
+    return stack;
 }
 
 // Returns the data of the top element.
 void *top(StackNode *stack)
 {
-
+    if (stack != NULL) {
+        return stack->data;
+    } else {
+        return NULL;
+    } 
 }
 
 // Clears stack and releases all memory.
 void clearStack(StackNode *stack)
 {
-
-}
\ No newline at end of file
+    while (stack != NULL) {
+        stack = pop(stack);
+    }
+}
diff --git a/I2_Dobble/stack.h b/I2_Dobble/stack.h
index f7d542d..641b400 100644
--- a/I2_Dobble/stack.h
+++ b/I2_Dobble/stack.h
@@ -7,7 +7,12 @@ The latest element is taken from the stack. */
 
 #include <stdlib.h>
 
-//TODO: passenden Datentyp als struct anlegen
+//DONE: passenden Datentyp als struct anlegen
+typedef struct Node
+{
+  void *data;
+  struct Node* next;
+} StackNode;
 
 // Pushes data as pointer onto the stack.
 StackNode *push(StackNode *stack, void *data);
diff --git a/I2_Dobble/stackTest.c b/I2_Dobble/stackTest.c
new file mode 100644
index 0000000..76173dc
--- /dev/null
+++ b/I2_Dobble/stackTest.c
@@ -0,0 +1,167 @@
+#include "stack.h"
+#include "unity/unity.h"
+#include "unity/unity_internals.h"
+
+/* wird nicht mehr gebraucht
+
+// Ein Blick in den Stack - listet den Stack-Inhalt der Reihe nach auf
+void inspectStack(StackNode *stack)
+{    
+    if (stack != NULL)
+    {
+        printf("Der Stack enthält die folgenden Elemente: %d", *(int*)stack->data);
+        while (stack->next != NULL)
+        {
+            printf(" %d", *(int*)stack->next->data);
+            stack = stack->next;
+        }
+        putchar('\n');
+    }
+    else
+    {
+        printf("Der Stack ist leer\n");
+    }
+}
+*/
+
+// Setup-Funktionen von Unity, die zumindest als Platzhalter definiert sein müssen
+void setUp(void) {};
+void tearDown(void) {};
+
+void test_createNodeAbortsOnZeroData(void)
+{
+    void *data = NULL;
+    StackNode *stack = NULL;
+    stack = push(stack, data);
+    TEST_ASSERT_EQUAL_PTR(stack, NULL);
+
+    clearStack(stack);
+}
+
+void test_createdNodeIsFirstInList(void)
+{
+    int data = 42;
+    StackNode *stack = NULL;
+    stack = push(stack, &data);
+    TEST_ASSERT_NOT_NULL(stack);
+    TEST_ASSERT_EQUAL_PTR(&data, stack->data);
+    TEST_ASSERT_NULL(stack->next);
+
+    clearStack(stack);
+}
+
+void test_createNodeCorrectOrder(void)
+{
+    int data[3] = {0, 1, 2};
+    StackNode *stack = NULL;
+    stack = push(stack, &data[2]);
+    stack = push(stack, &data[1]);
+    stack = push(stack, &data[0]);
+
+    TEST_ASSERT_NOT_NULL(stack);
+    TEST_ASSERT_EQUAL_PTR(&data[0], stack->data);
+    TEST_ASSERT_EQUAL_PTR(&data[1], stack->next->data);
+    TEST_ASSERT_EQUAL_PTR(&data[2], stack->next->next->data);
+    TEST_ASSERT_NULL(stack->next->next->next);
+
+    clearStack(stack);
+}
+
+void test_removeNodeAbortsOnZero(void)
+{
+    StackNode *stack = NULL;
+    TEST_ASSERT_NULL(pop(stack));
+
+    clearStack(stack);
+}
+
+void test_removeOnlyNodeEmptysList(void)
+{
+    int data = 42;
+    StackNode *stack = NULL;
+    stack = pop(push(stack, &data));
+
+    TEST_ASSERT_NULL(stack);
+
+    clearStack(stack);
+}
+
+void test_removeNodeRemovesFirst(void)
+{
+    int data[2] = {0, 1};
+    StackNode *stack = NULL;
+    stack = push(stack, &data[1]);
+    stack = push(stack, &data[0]);
+    stack = pop(stack);
+
+    TEST_ASSERT_NOT_NULL(stack);
+    TEST_ASSERT_EQUAL_PTR(&data[1], stack->data);
+    TEST_ASSERT_NULL(stack->next);
+
+    clearStack(stack);
+}
+
+void test_outputTopFailsOnZero(void)
+{
+    StackNode *stack = NULL;
+    
+    TEST_ASSERT_NULL(top(stack));
+
+    clearStack(stack);
+}
+
+void test_outputTopCorrect(void)
+{
+    int data[2] = {0, 1};
+    StackNode *stack = NULL;
+    stack = push(stack, &data[1]);
+    stack = push(stack, &data[0]);
+
+    TEST_ASSERT_NOT_NULL(stack);
+    TEST_ASSERT_EQUAL_PTR(top(stack), stack->data);
+
+    clearStack(stack);
+}
+
+
+/* Speicher freigabe lässt sich nicht mit Unity testen, am besten Programm mit valgrind ausführen
+void test_clearStackFreesMemory(void)
+{
+    int data[2] = {22, 17};
+    StackNode *lowNode = (StackNode *)malloc(sizeof(StackNode));
+    lowNode->next = NULL;
+    lowNode->data = &data[0];
+    StackNode *highNode = (StackNode *)malloc(sizeof(StackNode));
+    highNode->next = lowNode;
+    highNode->data = &data[1];
+    StackNode *stack = highNode;
+
+    clearStack(stack);
+
+    TEST_ASSERT_NULL(lowNode);
+    TEST_ASSERT_NULL(highNode);
+    TEST_ASSERT_NULL(stack);
+}
+*/
+
+int main()
+{
+    UNITY_BEGIN();
+
+    printf("\n============================\n Stack tests\n============================\n");
+    printf("-> Create Nodes (push)\n");
+    RUN_TEST(test_createNodeAbortsOnZeroData);
+    RUN_TEST(test_createdNodeIsFirstInList);
+    RUN_TEST(test_createNodeCorrectOrder);
+
+    printf("\n-> Remove Nodes (pop)\n");
+    RUN_TEST(test_removeNodeAbortsOnZero);
+    RUN_TEST(test_removeOnlyNodeEmptysList);
+    RUN_TEST(test_removeNodeRemovesFirst);
+
+    printf("\n-> Output Top (top)\n");
+    RUN_TEST(test_outputTopFailsOnZero);
+    RUN_TEST(test_outputTopCorrect);
+
+    return UNITY_END();
+}
\ No newline at end of file
diff --git a/I2_Dobble/test_stack.c b/I2_Dobble/test_stack.c
new file mode 100644
index 0000000..60fabd8
--- /dev/null
+++ b/I2_Dobble/test_stack.c
@@ -0,0 +1,80 @@
+#include <bits/types/stack_t.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "stack.h"
+
+void inspectStack(StackNode *stack)
+{    
+    if (stack != NULL)
+    {
+        printf("Der Stack enthält die folgenden Elemente: %d", *(int*)stack->value);
+        while (stack->next != NULL)
+        {
+            printf(" %d", *(int*)stack->next->value);
+            stack = stack->next;
+        }
+        putchar('\n');
+    }
+    else
+    {
+        printf("Der Stack ist leer\n");
+    }
+}
+
+int main()
+{
+    StackNode *stack;
+    stack = NULL; // initialisierung mit NULL -> leere Liste
+    
+    printf("...ein Element wird eingefügt...\n");
+    int toBeRemoved = 42;
+    stack = push(stack, &toBeRemoved);
+    
+    inspectStack(stack);
+
+    printf("...das Element wird wieder entfernt...\n");
+    stack = pop(stack);
+    
+    inspectStack(stack);
+    
+    printf("...pop auf leeren Stack...\n");
+    stack = pop(stack);
+    
+    inspectStack(stack);
+    putchar('\n');
+
+    int data[5] = {1, 2, 3, 4, 5};
+
+    // alle 5 werte der reihe nach auf den Satck legen - 1 unten ... 5 oben
+    for (int i = 0; i < 5; i++)
+    {
+        stack = push(stack, &data[i]);
+    }
+
+    
+    //alle Elemente mit Test-Funktion ausgeben
+    inspectStack(stack);
+    
+    // Elemente stück für Stück ausgeben und entfernen
+    printf("1. Element war: %d\n", *(int*)top(stack));
+    stack = pop(stack);
+    printf("2. Element war: %d\n", *(int*)top(stack));
+    stack = pop(stack);
+    printf("3. Element war: %d\n", *(int*)top(stack));
+    stack = pop(stack);
+    printf("4. Element war: %d\n", *(int*)top(stack));
+    stack = pop(stack);
+    printf("5. Element war: %d\n", *(int*)top(stack));
+}
+
+/*
+int main()
+{
+    UNITY_BEGIN();
+
+    printf("============================\n Stack tests\n============================\n");
+    RUN_TEST(test_createNodeFailsOnZeroData);
+
+    return UNITY_END();
+}
+*/