Do not start idle timer when lazy connection is already closed

When an operation fails because the underlying connection is closed, we
should never start an idle timer. There used to be a race condition that
the connection close event was detected before cancelling the pending
commands. We avoid this by checking the connection state before starting
an idle timer when an operation fails.

Author: clue

src/Io/LazyConnection.php

@@ -89,7 +89,7 @@ private function idle()
     {
         --$this->pending;
 
-        if ($this->pending < 1 && $this->idlePeriod >= 0) {
+        if ($this->pending < 1 && $this->idlePeriod >= 0 && $this->connecting !== null) {
             $this->idleTimer = $this->loop->addTimer($this->idlePeriod, function () {
                 $this->connecting->then(function (ConnectionInterface $connection) {
                     $this->disconnecting = $connection;

tests/Io/LazyConnectionTest.php

@@ -513,6 +513,29 @@ public function testPingWillRejectAndStartTimerWhenPingFromUnderlyingConnectionR
         $ret->then($this->expectCallableNever(), $this->expectCallableOnceWith($error));
     }
 
+    public function testPingWillRejectAndNotStartIdleTimerWhenPingFromUnderlyingConnectionRejectsBecauseConnectionIsDead()
+    {
+        $error = new \RuntimeException();
+
+        $base = $this->getMockBuilder('React\MySQL\Io\LazyConnection')->setMethods(array('ping', 'close'))->disableOriginalConstructor()->getMock();
+        $base->expects($this->once())->method('ping')->willReturnCallback(function () use ($base, $error) {
+            $base->emit('close');
+            return \React\Promise\reject($error);
+        });
+        $base->expects($this->never())->method('close');
+
+        $factory = $this->getMockBuilder('React\MySQL\Factory')->disableOriginalConstructor()->getMock();
+        $factory->expects($this->once())->method('createConnection')->willReturn(\React\Promise\resolve($base));
+
+        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop->expects($this->never())->method('addTimer');
+
+        $connection = new LazyConnection($factory, '', $loop);
+
+        $ret = $connection->ping();
+        $ret->then($this->expectCallableNever(), $this->expectCallableOnceWith($error));
+    }
+
     public function testQuitResolvesAndEmitsCloseImmediatelyWhenConnectionIsNotAlreadyPending()
     {
         $factory = $this->getMockBuilder('React\MySQL\Factory')->disableOriginalConstructor()->getMock();