Improve code coverage to 100%

src/Buffer.php

@@ -79,10 +79,6 @@ public function close()
 
     public function end()
     {
-        if ($this->writable === false) {
-            return;
-        }
-
         $this->writable = false;
 
         if (!$this->outgoing) {

src/Socket.php

@@ -102,11 +102,10 @@ private function sanitizeAddress($address)
             return null;
         }
 
-        // this is an IPv6 address which includes colons but no square brackets
+        // check if this is an IPv6 address which includes multiple colons but no square brackets (PHP < 7.3)
         $pos = \strrpos($address, ':');
         if ($pos !== false && \strpos($address, ':') < $pos && \substr($address, 0, 1) !== '[') {
-            $port = \substr($address, $pos + 1);
-            $address = '[' . \substr($address, 0, $pos) . ']:' . $port;
+            $address = '[' . \substr($address, 0, $pos) . ']:' . \substr($address, $pos + 1); // @codeCoverageIgnore
         }
         return $address;
     }

tests/BufferTest.php

@@ -0,0 +1,72 @@
+<?php
+
+namespace React\Tests\Datagram;
+
+use PHPUnit\Framework\TestCase;
+use React\Datagram\Buffer;
+
+class BufferTest extends TestCase
+{
+    public function testSendAddsSocketToLoop()
+    {
+        $socket = stream_socket_client('udp://127.0.0.1:8000');
+
+        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop->expects($this->once())->method('addWriteStream')->with($socket);
+
+        $client = new Buffer($loop, $socket);
+
+        $client->send('foo');
+    }
+
+    public function testSendAfterCloseIsNoop()
+    {
+        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop->expects($this->never())->method('addWriteStream');
+
+        $socket = stream_socket_client('udp://127.0.0.1:8000');
+
+        $client = new Buffer($loop, $socket);
+
+        $client->close();
+        $client->send('foo');
+    }
+
+    public function testCloseAfterSendAddsSocketToLoopRemovesSocketFromLoopAgain()
+    {
+        $socket = stream_socket_client('udp://127.0.0.1:8000');
+
+        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+        $loop->expects($this->once())->method('addWriteStream')->with($socket);
+        $loop->expects($this->once())->method('removeWriteStream')->with($socket);
+
+        $client = new Buffer($loop, $socket);
+
+        $client->send('foo');
+        $client->close();
+    }
+
+    public function testCloseTwiceEmitsCloseEventOnce()
+    {
+        $loop = $this->getMockBuilder('React\EventLoop\LoopInterface')->getMock();
+
+        $socket = stream_socket_client('udp://127.0.0.1:8000');
+
+        $client = new Buffer($loop, $socket);
+
+        $closed = 0;
+        $client->on('close', function () use (&$closed) {
+            ++$closed;
+        });
+
+        $this->assertEquals(0, $closed);
+
+        $client->close();
+
+        $this->assertEquals(1, $closed);
+
+        $client->close();
+
+        $this->assertEquals(1, $closed);
+    }
+}