Add Test for positive integer exponent function

test/test_exponent.c

@@ -12,9 +12,16 @@ void tearDown(void)
 {
 }
 
-void test_IntegerExponent_NeedToImplement(void)
-{
-    TEST_IGNORE_MESSAGE("Integer Exponent needs to be implemented");
+void test_IntegerExponent_ForPositiveExponent(void){
+    int r1, r2, r3;
+
+    r1 = expI(2, -2);
+    r2 = expI(3, -3);
+    r3 = expI(4, 5);
+
+    TEST_ASSERT_EQUAL_INT(4, r1);
+    TEST_ASSERT_EQUAL_INT(-27, r2);
+    TEST_ASSERT_EQUAL_INT(625, r3);  
 }