node/convert: support conversion for std::string_view (#1148)

test/node/node_test.cpp

@@ -356,6 +356,15 @@ TEST(NodeTest, ConstInteratorOnSequence) {
   EXPECT_EQ(3, count);
 }
 
+#if __cplusplus >= 201703L
+TEST(NodeTest, StdStringViewAsKey) {
+  Node node;
+  std::string_view key = "username";
+  node[key] = "monkey";
+  EXPECT_EQ("monkey", node[key].as<std::string>());
+}
+#endif
+
 TEST(NodeTest, SimpleSubkeys) {
   Node node;
   node["device"]["udid"] = "12345";