Replaced printTo() with serializeJson()

* Added `serializeJson()` and `serializeJsonPretty()`
* Added `measureJson()` and `measureJsonPretty()`
* Removed `printTo()` and `prettyPrintTo()`
* Removed `measureLength()` and `measurePrettyLength()`

test/JsonSerializer/JsonObject.cpp

@@ -0,0 +1,114 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+#include <string>
+
+void check(const JsonObject &obj, const std::string &expected) {
+  char actual[256];
+  size_t actualLen = serializeJson(obj, actual);
+  size_t measuredLen = measureJson(obj);
+
+  REQUIRE(expected == actual);
+  REQUIRE(expected.size() == actualLen);
+  REQUIRE(expected.size() == measuredLen);
+}
+
+TEST_CASE("serializeJson(JsonObject)") {
+  DynamicJsonObject obj;
+
+  SECTION("EmptyObject") {
+    check(obj, "{}");
+  }
+
+  SECTION("TwoStrings") {
+    obj["key1"] = "value1";
+    obj.set("key2", "value2");
+
+    check(obj, "{\"key1\":\"value1\",\"key2\":\"value2\"}");
+  }
+
+  SECTION("RemoveFirst") {
+    obj["key1"] = "value1";
+    obj["key2"] = "value2";
+    obj.remove("key1");
+
+    check(obj, "{\"key2\":\"value2\"}");
+  }
+
+  SECTION("RemoveLast") {
+    obj["key1"] = "value1";
+    obj["key2"] = "value2";
+    obj.remove("key2");
+
+    check(obj, "{\"key1\":\"value1\"}");
+  }
+
+  SECTION("RemoveUnexistingKey") {
+    obj["key1"] = "value1";
+    obj["key2"] = "value2";
+    obj.remove("key3");
+
+    check(obj, "{\"key1\":\"value1\",\"key2\":\"value2\"}");
+  }
+
+  SECTION("ReplaceExistingKey") {
+    obj["key"] = "value1";
+    obj["key"] = "value2";
+
+    check(obj, "{\"key\":\"value2\"}");
+  }
+
+  SECTION("TwoIntegers") {
+    obj["a"] = 1;
+    obj.set("b", 2);
+    check(obj, "{\"a\":1,\"b\":2}");
+  }
+
+  SECTION("RawJson") {
+    obj["a"] = RawJson("[1,2]");
+    obj.set("b", RawJson("[4,5]"));
+    check(obj, "{\"a\":[1,2],\"b\":[4,5]}");
+  }
+
+  SECTION("Two doubles") {
+    obj["a"] = 12.34;
+    obj.set("b", 56.78);
+    check(obj, "{\"a\":12.34,\"b\":56.78}");
+  }
+
+  SECTION("TwoNull") {
+    obj["a"] = static_cast<char *>(0);
+    obj.set("b", static_cast<char *>(0));
+    check(obj, "{\"a\":null,\"b\":null}");
+  }
+
+  SECTION("TwoBooleans") {
+    obj["a"] = true;
+    obj.set("b", false);
+    check(obj, "{\"a\":true,\"b\":false}");
+  }
+
+  SECTION("ThreeNestedArrays") {
+    DynamicJsonArray b, c;
+
+    obj.createNestedArray("a");
+    obj["b"] = b;
+    obj.set("c", c);
+
+    check(obj, "{\"a\":[],\"b\":[],\"c\":[]}");
+  }
+
+  SECTION("ThreeNestedObjects") {
+    DynamicJsonObject b;
+    DynamicJsonObject c;
+
+    obj.createNestedObject("a");
+    obj["b"] = b;
+    obj.set("c", c);
+
+    check(obj, "{\"a\":{},\"b\":{},\"c\":{}}");
+  }
+}