Add testcases for IPAddress::toString()

Author: pennam

Diff for: test/CMakeLists.txt

@@ -29,6 +29,7 @@ set(TEST_SRCS
   src/Common/test_map.cpp
   src/Common/test_max.cpp
   src/Common/test_min.cpp
+  src/IPAddress/test_toString.cpp
   src/IPAddress/test_fromString.cpp
   src/IPAddress/test_fromString6.cpp
   src/IPAddress/test_IPAddress.cpp

Diff for: test/src/IPAddress/test_toString.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2020 Arduino.  All rights reserved.
+ */
+
+/**************************************************************************************
+ * INCLUDE
+ **************************************************************************************/
+
+#include <catch.hpp>
+
+#include <String.h>
+#include <IPAddress.h>
+
+/**************************************************************************************
+ * TEST CODE
+ **************************************************************************************/
+
+TEST_CASE ("Extract valid string from IPv4address", "[IPAddress-toString-01]")
+{
+  arduino::IPAddress ip(129,168,1,2);
+
+  REQUIRE(ip.toString().equals("129.168.1.2") == true);
+}
+
+TEST_CASE ("Extract valid ipv6 string from IPv6address", "[IPAddress-toString-02]")
+{
+  arduino::IPAddress ip(0x20,0x01, 0xd,0xb8, 1,2, 3,4, 5,6, 7,8, 9,0xa, 0xb,0xc);
+
+  REQUIRE(ip.toString().equals("2001:0db8:0102:0304:0506:0708:090a:0b0c") == true);
+}
+
+TEST_CASE ("Extract 0.0.0.0 string from uninitialized IP address", "[IPAddress-toString-03]")
+{
+  arduino::IPAddress ip;
+
+  REQUIRE(ip.toString().equals("0.0.0.0") == true);
+}