Added arithmetic addition including unittest

src/arithmeticAddition.c

@@ -0,0 +1,13 @@
+#include "arithmeticAddition.h"
+#include <stdio.h>
+#include <limits.h>
+#include <stdlib.h>
+
+int* addition_integer(int num1, int num2) {
+    if ((num2 > 0 && num1 > INT_MAX - num2) || (num2 < 0 && num1 < INT_MIN - num2)) {
+        return NULL;
+    }
+    int* result = malloc(sizeof(int));
+    *result = num1 + num2;
+    return result;
+}

src/arithmeticAddition.h

@@ -0,0 +1,6 @@
+#ifndef THEADMIRALS_ARITHMETICADDITION_H
+#define THEADMIRALS_ARITHMETICADDITION_H
+
+int* addition_integer(int, int);
+
+#endif //THEADMIRALS_ARITHMETICADDITION_H

test/test_arithmeticAddition.c

@@ -0,0 +1,24 @@
+#include "../src/arithmeticAddition.h"
+#include "unity.h"
+#include "limits.h"
+
+void setUp(void) {
+    // set stuff up here
+}
+
+void tearDown(void) {
+    // clean stuff up here
+}
+
+void test_arithmeticAddition_numberplusnumberequalsnumber(void) {
+    int expectedResult = 8;
+    int* result;
+    result = addition_integer(5, 3);
+    TEST_ASSERT_EQUAL_INT(expectedResult, *result);
+}
+
+void test_arithmeticAddition_numberplusmaxintegervalueequalsnull(void) {
+    int* result;
+    result = addition_integer(INT_MAX, 1);
+    TEST_ASSERT_NULL(result);
+}