Prevent enqueuing sequences after fatal error

fixes #400

Author: dougwilson

lib/protocol/Protocol.js

@@ -143,7 +143,10 @@ Protocol.prototype._validateEnqueue = function(sequence) {
   var prefixBefore = prefix + ' before ';
   var prefixAfter = prefix + ' after ';
 
-  if (this._quitSequence) {
+  if (this._fatalError) {
+    err      = new Error(prefixAfter + 'fatal error.');
+    err.code = 'PROTOCOL_ENQUEUE_AFTER_FATAL_ERROR';
+  } else if (this._quitSequence) {
     err      = new Error(prefixAfter + 'invoking quit.');
     err.code = 'PROTOCOL_ENQUEUE_AFTER_QUIT';
   } else if (this._destroyed) {

test/integration/connection/test-connection-error.js

@@ -0,0 +1,64 @@
+var common     = require('../../common');
+var connection = common.createConnection({port: common.fakeServerPort});
+var assert     = require('assert');
+
+var server = common.createFakeServer();
+
+var connectErr;
+var finalErr;
+var queryErr1;
+var queryErr2;
+var queryErr3;
+var timeout;
+server.listen(common.fakeServerPort, function(err) {
+  if (err) throw err;
+  var waitCount = 4;
+
+  connection.connect(function(err) {
+    connectErr = err;
+    if (!--waitCount) end();
+  });
+
+  connection.query('SELECT 1', function(err) {
+    queryErr1 = err;
+    connection.query('SELECT 1', function(err) {
+      finalErr = err;
+      if (!--waitCount) end();
+    });
+  });
+
+  process.nextTick(function() {
+    connection.query('SELECT 1', function(err) {
+      queryErr2 = err;
+      if (!--waitCount) end();
+    });
+  });
+
+  setTimeout(function() {
+    connection.query('SELECT 1', function(err) {
+      queryErr3 = err;
+      if (!--waitCount) end();
+    });
+  }, 200);
+
+  timeout = setTimeout(end, 2000);
+});
+
+function end() {
+  if (timeout) clearTimeout(timeout);
+  server.destroy();
+}
+
+server.on('connection', function(incomingConnection) {
+  var errno = 1130; // ER_HOST_NOT_PRIVILEGED
+  incomingConnection.deny('You suck.', errno);
+});
+
+process.on('exit', function() {
+  assert.ok(connectErr);
+  assert.ok(queryErr1);
+  assert.ok(queryErr2);
+  assert.ok(queryErr3);
+  assert.ok(finalErr);
+  assert.equal(finalErr.code, 'PROTOCOL_ENQUEUE_AFTER_FATAL_ERROR');
+});