add arduino json lib

#182

lib/ArduinoJson/test/JsonWriter/writeString.cpp

@@ -0,0 +1,61 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#include <catch.hpp>
+
+#include <ArduinoJson/Serialization/JsonWriter.hpp>
+#include <ArduinoJson/Serialization/StaticStringBuilder.hpp>
+
+using namespace ArduinoJson::Internals;
+
+void check(const char* input, std::string expected) {
+  char output[1024];
+  StaticStringBuilder sb(output, sizeof(output));
+  JsonWriter<StaticStringBuilder> writer(sb);
+  writer.writeString(input);
+  REQUIRE(expected == output);
+  REQUIRE(writer.bytesWritten() == expected.size());
+}
+
+TEST_CASE("JsonWriter::writeString()") {
+  SECTION("Null") {
+    check(0, "null");
+  }
+
+  SECTION("EmptyString") {
+    check("", "\"\"");
+  }
+
+  SECTION("QuotationMark") {
+    check("\"", "\"\\\"\"");
+  }
+
+  SECTION("ReverseSolidus") {
+    check("\\", "\"\\\\\"");
+  }
+
+  SECTION("Solidus") {
+    check("/", "\"/\"");  // but the JSON format allows \/
+  }
+
+  SECTION("Backspace") {
+    check("\b", "\"\\b\"");
+  }
+
+  SECTION("Formfeed") {
+    check("\f", "\"\\f\"");
+  }
+
+  SECTION("Newline") {
+    check("\n", "\"\\n\"");
+  }
+
+  SECTION("CarriageReturn") {
+    check("\r", "\"\\r\"");
+  }
+
+  SECTION("HorizontalTab") {
+    check("\t", "\"\\t\"");
+  }
+}