Fixes an event handler leak.

Includes a test. Also includes async as a devDependency.

test/copy-to.js

@@ -1,20 +1,21 @@
 var assert = require('assert')
 var gonna = require('gonna')
 
-var concat = require('concat-stream')
 var _ = require('lodash')
+var async = require('async')
+var concat = require('concat-stream')
 var pg = require('pg.js')
 
+var copy = require('../').to
+
+var client = function() {
+  var client = new pg.Client()
+  client.connect()
+  return client
+}
+
 var testRange = function(top) {
-  var client = function() {
-    var client = new pg.Client()
-    client.connect()
-    return client
-  }
-
   var fromClient = client()
-  var copy = require('../').to
-
   var txt = 'COPY (SELECT * from generate_series(0, ' + (top - 1) + ')) TO STDOUT'
 
   var stream = fromClient.query(copy(txt))
@@ -32,3 +33,27 @@ var testRange = function(top) {
 }
 
 testRange(10000)
+
+var testLeak = function(rounds) {
+  var fromClient = client()
+  var txt = 'COPY (SELECT 10) TO STDOUT'
+
+  var runStream = function(num, callback) {
+    var stream = fromClient.query(copy(txt))
+    stream.on('data', function(data) {
+      // Just throw away the data.
+    })
+    stream.on('end', callback)
+    stream.on('error', callback)
+  }
+
+  async.timesSeries(rounds, runStream, function(err) {
+    assert.equal(err, null)
+    assert.equal(fromClient.connection.stream.listeners('data').length, 1)
+    assert.equal(fromClient.connection.stream.listeners('end').length, 2)
+    assert.equal(fromClient.connection.stream.listeners('close').length, 0)
+    fromClient.end()
+  })
+}
+
+testLeak(5)