diff --git a/makefile b/makefile
index 1f15f75..c816795 100644
--- a/makefile
+++ b/makefile
@@ -36,7 +36,13 @@ $(program_obj_filesobj_files): %.o: %.c
 # Unit Tests
 # --------------------------
 unitTests:
-	echo "needs to be implemented"
+TEST_BIN = runTests
+
+unitTests: stack.o test_stack.o
+	$(CC) $(FLAGS) -I$(unityfolder) -o $(TEST_BIN) stack.o test_stack.o $(unityfolder)/unity.c
+
+test_stack.o: test_stack.c
+	$(CC) $(FLAGS) -I$(unityfolder) -c test_stack.c -o test_stack.o
 
 # --------------------------
 # Clean
diff --git a/stack.h b/stack.h
index 6d5dce9..c835596 100644
--- a/stack.h
+++ b/stack.h
@@ -13,6 +13,7 @@ typedef struct StackNode {
 
   void *data;
   struct StackNode *next;
+  struct StackNode *prev;
 
 } StackNode;
 
diff --git a/test_stack.c b/test_stack.c
new file mode 100644
index 0000000..dd9a6ca
--- /dev/null
+++ b/test_stack.c
@@ -0,0 +1,59 @@
+#include "unity.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "stack.h"
+
+void test_createNode(void) {
+
+  int testInt = 26;
+
+  StackNode *testNode = createNode(&testInt);
+
+  TEST_ASSERT_NOT_NULL(testNode);
+
+  TEST_ASSERT_EQUAL_PTR(&testInt, testNode->data);
+
+  TEST_ASSERT_NULL(testNode->next);
+
+  free(testNode);
+}
+
+void test_pushDataToStack(void) {}
+
+void test_deleteTopElement(void) {}
+
+void test_returnData(void) {}
+
+void test_clearStack(void) {
+
+  int testInts[] = {1, 2, 3, 4, 5};
+  StackNode *testStack = NULL;
+
+  for (int i = 0; i < 5; i++) {
+
+    testStack = push(testStack, &testInts[i]);
+  }
+
+  clearStack(testStack);
+  TEST_ASSERT_NULL(testStack);
+}
+
+void setUp(void) {}
+void tearDown(void) {}
+
+int main(void) {
+
+  UNITY_BEGIN();
+
+  printf("------------------------stack test------------------------\n");
+  RUN_TEST(test_createNode);
+  RUN_TEST(test_pushDataToStack);
+  RUN_TEST(test_deleteTopElement);
+  RUN_TEST(test_returnData);
+  RUN_TEST(test_clearStack);
+  RUN_TEST(test_clearStack);
+
+  return UNITY_END();
+}
\ No newline at end of file