add variant test

test/variant.cpp

@@ -0,0 +1,18 @@
+#include <iostream>
+#include "gtest/gtest.h"
+
+#include <llmr/style/value.hpp>
+#include <boost/lexical_cast.hpp>
+
+using namespace llmr;
+
+TEST(Variant, toString) {
+    EXPECT_EQ("lord", llmr::toString( (std::string)"lord" ));
+    EXPECT_EQ("36", llmr::toString( (uint64_t)36 ));
+    EXPECT_EQ("-239", llmr::toString( (int64_t)-239 ));
+    EXPECT_EQ("0", llmr::toString( (int64_t)0 ));
+    EXPECT_EQ("3.14159268", llmr::toString( (double)3.14159268 ));
+    EXPECT_EQ("3.1415926535897931", llmr::toString( (double)3.1415926535897931 ));
+    EXPECT_EQ("true", llmr::toString( true ));
+    EXPECT_EQ("false", llmr::toString( false ));
+}