Implemented unittest for input handler method

test/test_inputHandler.c

@@ -0,0 +1,18 @@
+#include "../src/inputHandler.h"
+#include "unity.h"
+
+void setUp(void) {
+    // set stuff up here
+}
+
+void tearDown(void) {
+    // clean stuff up here
+}
+
+
+void test_inputHandler_returntwoforinputminus(void) {
+    int expectedResult = 2;
+    int result;
+    result = getOperationIdBySymbol('-');
+    TEST_ASSERT_EQUAL_INT(expectedResult, result);
+}