Add a unit test, not deliver will when DISCONNECT

lib/client.js

@@ -267,8 +267,9 @@ Client.prototype.close = function (done) {
           }
         }
       })
-      that.will = null // this function might be called twice
     }
+    that.will = null // this function might be called twice
+    that._will = null
 
     conn.removeAllListeners('error')
     conn.on('error', nop)

lib/handlers/index.js

@@ -48,6 +48,7 @@ function handle (client, packet, done) {
       handlePing(client, packet, done)
       break
     case 'disconnect':
+      // [MQTT-3.14.4-1]
       client.disconnected = true
       client.conn.end()
       return

test/will.js

@@ -3,9 +3,9 @@
 var test = require('tape').test
 var memory = require('aedes-persistence')
 var helper = require('./helper')
+var aedes = require('../')
 var setup = helper.setup
 var connect = helper.connect
-var aedes = require('../')
 
 function willConnect (s, opts, connected) {
   opts = opts || {}
@@ -297,3 +297,18 @@ test('does not deliver will if keepalive is triggered during authentication', fu
 
   willConnect(setup(broker), opts)
 })
+
+// [MQTT-3.14.4-1]
+test('does not deliver will when client sends a DISCONNECT', function (t) {
+  var broker = aedes()
+  var s = willConnect(setup(broker))
+
+  s.inStream.end({
+    cmd: 'disconnect'
+  })
+
+  s.broker.mq.on('mywill', function (packet, cb) {
+    t.fail(packet)
+  })
+  broker.on('closed', t.end.bind(t))
+})