Json telemetry

tests/RenderCadenceCompositorJsonWriterTests.cpp

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+#include "JsonWriter.h"
+
+#include <iostream>
+#include <stdexcept>
+#include <string>
+
+namespace
+{
+int gFailures = 0;
+
+void Expect(bool condition, const std::string& message)
+{
+	if (condition)
+		return;
+
+	++gFailures;
+	std::cerr << "FAILED: " << message << "\n";
+}
+
+void ExpectEquals(const std::string& actual, const std::string& expected, const std::string& message)
+{
+	if (actual == expected)
+		return;
+
+	++gFailures;
+	std::cerr << "FAILED: " << message << "\n"
+		<< "expected: " << expected << "\n"
+		<< "actual:   " << actual << "\n";
+}
+
+void TestEscapesStrings()
+{
+	using RenderCadenceCompositor::JsonWriter;
+
+	ExpectEquals(
+		JsonWriter::EscapeString("quote\" slash\\ newline\n tab\t"),
+		"quote\\\" slash\\\\ newline\\n tab\\t",
+		"string escape handles common escaped characters");
+
+	std::string control;
+	control.push_back(static_cast<char>(0x01));
+	ExpectEquals(JsonWriter::EscapeString(control), "\\u0001", "string escape handles control characters");
+}
+
+void TestObjectSerialization()
+{
+	using RenderCadenceCompositor::JsonWriter;
+
+	JsonWriter writer;
+	writer.BeginObject();
+	writer.KeyString("name", "cadence");
+	writer.KeyDouble("renderFps", 59.94);
+	writer.KeyBool("healthy", true);
+	writer.KeyNull("error");
+	writer.EndObject();
+
+	ExpectEquals(
+		writer.StringValue(),
+		"{\"name\":\"cadence\",\"renderFps\":59.94,\"healthy\":true,\"error\":null}",
+		"object serialization is compact and ordered");
+}
+
+void TestNestedArrays()
+{
+	using RenderCadenceCompositor::JsonWriter;
+
+	JsonWriter writer;
+	writer.BeginObject();
+	writer.Key("levels");
+	writer.BeginArray();
+	writer.String("log");
+	writer.String("warning");
+	writer.String("error");
+	writer.EndArray();
+	writer.Key("counts");
+	writer.BeginObject();
+	writer.KeyUInt("queued", 3);
+	writer.KeyInt("delta", -1);
+	writer.EndObject();
+	writer.EndObject();
+
+	ExpectEquals(
+		writer.StringValue(),
+		"{\"levels\":[\"log\",\"warning\",\"error\"],\"counts\":{\"queued\":3,\"delta\":-1}}",
+		"nested arrays and objects serialize correctly");
+}
+
+void TestMisuseThrows()
+{
+	using RenderCadenceCompositor::JsonWriter;
+
+	JsonWriter writer;
+	bool threw = false;
+	try
+	{
+		writer.BeginObject();
+		writer.Key("missing");
+		writer.EndObject();
+	}
+	catch (const std::logic_error&)
+	{
+		threw = true;
+	}
+	Expect(threw, "ending an object with a key missing a value throws");
+}
+}
+
+int main()
+{
+	TestEscapesStrings();
+	TestObjectSerialization();
+	TestNestedArrays();
+	TestMisuseThrows();
+
+	if (gFailures != 0)
+	{
+		std::cerr << gFailures << " RenderCadenceCompositorJsonWriter test failure(s).\n";
+		return 1;
+	}
+
+	std::cout << "RenderCadenceCompositorJsonWriter tests passed.\n";
+	return 0;
+}