Fix NoticeResponse test and handle other messages (#52)

message-formats.js

@@ -7,11 +7,19 @@
  * https://www.postgresql.org/docs/current/static/protocol-flow.html
  */
 module.exports = {
-  ErrorResponse:    0x45,
-  CopyInResponse:   0x47,
-  CopyOutResponse:  0x48,
-  CopyBothResponse: 0x57,
-  CopyData:         0x64,
-  CopyDone:         0x63,
-  CopyFail:         0x66
+  ErrorResponse:        0x45, // E
+  CopyInResponse:       0x47, // G
+  CopyOutResponse:      0x48, // H
+  CopyBothResponse:     0x57, // W
+  CopyDone:             0x63, // c
+  CopyData:             0x64, // d
+  CopyFail:             0x66, // f
+
+  // It is possible for NoticeResponse and ParameterStatus messages to be interspersed between CopyData messages;
+  // frontends must handle these cases, and should be prepared for other asynchronous message types as well
+  // (see Section 50.2.6).
+  // Otherwise, any message type other than CopyData or CopyDone may be treated as terminating copy-out mode.
+  NotificationResponse: 0x41, // A
+  NoticeResponse:       0x4E, // N
+  ParameterStatus:      0x53  // S
 }