Reorganized writer classes

extras/tests/JsonSerializer/CustomWriter.cpp

@@ -5,18 +5,29 @@
 #include <ArduinoJson.h>
 #include <catch.hpp>
 
-struct CustomWriter {
-  std::string str;
+class CustomWriter {
+ public:
+  CustomWriter() {}
 
   size_t write(uint8_t c) {
-    str.append(1, static_cast<char>(c));
+    _str.append(1, static_cast<char>(c));
     return 1;
   }
 
   size_t write(const uint8_t *s, size_t n) {
-    str.append(reinterpret_cast<const char *>(s), n);
+    _str.append(reinterpret_cast<const char *>(s), n);
     return n;
   }
+
+  const std::string &str() const {
+    return _str;
+  }
+
+ private:
+  CustomWriter(const CustomWriter &);  // non-copiable
+  CustomWriter &operator=(const CustomWriter &);
+
+  std::string _str;
 };
 
 TEST_CASE("CustomWriter") {
@@ -29,13 +40,13 @@ TEST_CASE("CustomWriter") {
     CustomWriter writer;
     serializeJson(array, writer);
 
-    REQUIRE("[4,2]" == writer.str);
+    REQUIRE("[4,2]" == writer.str());
   }
 
   SECTION("serializeJsonPretty") {
     CustomWriter writer;
     serializeJsonPretty(array, writer);
 
-    REQUIRE("[\r\n  4,\r\n  2\r\n]" == writer.str);
+    REQUIRE("[\r\n  4,\r\n  2\r\n]" == writer.str());
   }
 }