change direction right E --> S

src/main/c/labyrinth.c

@@ -10,5 +10,8 @@ void turn_direction_right(Direction *direction){
         case N:
             *direction = E;
             break;
+        case E:
+            *direction = S;
+            break;
     }
 }

src/test/c/test_labyrinth.c

@@ -25,3 +25,15 @@ void test_change_direction_from_N_expected_E(void)
 	TEST_ASSERT_TRUE(expected == actual);
 }
 
+void test_turn_direction_right_from_E_expected_S(void)
+{
+    /* arrange */
+    Direction actual = E;
+    Direction expected = S;
+
+    /* act */
+    turn_direction_right(&actual);
+
+    /* assert */
+	TEST_ASSERT_TRUE(expected == actual);
+}