Ensure that dot stuffing is done before encoding (#22)

* Added test with mesage body that breaks if dot stuffing is done before encoding. Changed `Writer::writeFiltered` to use `stream_filter_prepend`.

* Added comment since we have no assertions

src/Writer.php

@@ -106,7 +106,7 @@ public function writeBase64($input): void
      */
     protected function writeFiltered($input, string $filter, array $options = []): void
     {
-        $filter = stream_filter_append($this->output, $filter, STREAM_FILTER_WRITE, $options);
+        $filter = stream_filter_prepend($this->output, $filter, STREAM_FILTER_WRITE, $options);
 
         $this->write($input);
 

tests/integration/MailServiceCest.php

@@ -3,6 +3,8 @@
 namespace Kodus\Mail\Test\Integration;
 
 use IntegrationTester;
+use Kodus\Mail\Address;
+use Kodus\Mail\Message;
 use Kodus\Mail\SMTP\Authenticator\NoAuthenticator;
 use Kodus\Mail\SMTP\SMTPMailService;
 use Kodus\Mail\Test\TestMessageFactory;
@@ -31,4 +33,30 @@ public function sendMail(IntegrationTester $I)
             $service->send($message);
         }
     }
+
+    public function ensureDotStuffingHappensBeforeQuotePrintableEncode(IntegrationTester $I)
+    {
+        $text_body = <<<EOT
+        Test mail 1234567890 1234567890 1234567890 1234567890 1234567890 1234567890.
+        More text.
+        EOT;
+
+        $service = new SMTPMailService(
+            $I->createSocketConnector(), new NoAuthenticator(), "localhost"
+        );
+
+        $message = new Message(
+            new Address("[email protected]", "Rasmus åh Schultz"),
+            new Address("[email protected]"),
+            "Hey, Rasmus! I like ÆØÅæøå!",
+            $text_body,
+        );
+
+        $message->setDate("Thu, 15 Sep 2016 17:20:54 +0200");
+
+        $message->setSender(new Address("[email protected]"));
+
+        // Throws \Kodus\Mail\SMTP\UnexpectedCodeException if dot stuffing is after encoding
+        $service->send($message);
+    }
 }