Added unit tests for Return Values

Author: andreagilardoni

test/CMakeLists.txt

@@ -50,6 +50,7 @@ set(TEST_SRCS
   src/Common/test_max.cpp
   src/Common/test_min.cpp
   src/ErrorCodes/test_ErrorCodes.cpp
+  src/ErrorCodes/test_ReturnValues.cpp
   src/IPAddress/test_toString.cpp
   src/IPAddress/test_fromString.cpp
   src/IPAddress/test_fromString6.cpp

test/src/ErrorCodes/test_ReturnValues.cpp

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2020 Arduino.  All rights reserved.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+/**************************************************************************************
+ * INCLUDE
+ **************************************************************************************/
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <api/ErrorCodes.h>
+
+using namespace arduino;
+
+/**************************************************************************************
+ * TEST CODE
+ **************************************************************************************/
+
+int test_int(int i) {
+  return i;
+}
+
+ReturnValue test(int i) {
+  return i;
+}
+
+TEST_CASE ("A ReturnValue can be evaluated as boolean", "[ReturnValues-Evaluation]") {
+  // Default constructor takes an integer implicitly, if negative it means error
+  REQUIRE((bool)ReturnValue(1) == true);
+  REQUIRE((bool)ReturnValue(-12) == false);
+}
+
+TEST_CASE ("A ReturnValue can be substituted to int in a function return value", "[ReturnValues-Evaluation]") {
+  REQUIRE((bool)test(1)     == true);
+  REQUIRE((bool)test(-123)  == false);
+  REQUIRE(test_int(1)       == (int)test(1));
+  REQUIRE(test_int(-123)    == (int)test(-123));
+}
+
+TEST_CASE ("A ReturnValue can be instantiated with explicit error code and value", "[ReturnValues-Evaluation]") {
+  THEN("It can take a negative value as value and still be successful") {
+    auto rv = ReturnValue(-1231, ArduinoSuccess);
+
+    REQUIRE((bool)rv == true);
+  }
+  THEN("It can take both a value and an error code ") {
+    auto rv = ReturnValue(-1231, ArduinoError);
+
+    REQUIRE((bool)rv == false);
+    REQUIRE(rv.value == -1231);
+    REQUIRE(rv.error == ArduinoError);
+  }
+}