Make the SMTP connect timeout configurable

src/ProviderClient/GenericProviderClient.php

@@ -19,6 +19,11 @@
 
 class GenericProviderClient
 {
+    /**
+     * Seconds to wait for an MX server to accept the TCP connection
+     */
+    public const int DEFAULT_CONNECT_TIMEOUT = 30;
+
     /**
      * Host domain to use to connect to the MX servers
      * Warning: some MX servers require the domain to point to an IP with a valid reverse DNS record
@@ -30,7 +35,8 @@ public function __construct(
         private readonly BounceIsCausedByUnknownUserSpecification $bounceIsCausedByUnknownUserSpecification,
         private readonly BounceIsCausedByInactiveUserSpecification $bounceIsCausedByInactiveUserSpecification,
         private readonly BounceTypeResolver $bounceTypeResolver,
-        private readonly string $host
+        private readonly string $host,
+        private readonly int $connectTimeout = self::DEFAULT_CONNECT_TIMEOUT
     ) {
     }
 
@@ -39,11 +45,11 @@ public function __construct(
      */
     public function check(string $email, string $mxServer): ValidationStatusDtoInterface
     {
-        $connection = new SMTP();
+        $connection = $this->createConnection();
         $connection->Debugoutput = $this->logger;
         try {
             // Based on https://github.com/PHPMailer/PHPMailer/blob/master/examples/smtp_check.phps
-            if (!$connection->connect($mxServer)) {
+            if (!$connection->connect($mxServer, null, $this->connectTimeout)) {
                 throw new SmtpConnectionRuntimeException(
                     sprintf('Failed to connect to server: %s', $mxServer),
                     0,
@@ -144,4 +150,9 @@ public function check(string $email, string $mxServer): ValidationStatusDtoInter
             throw $exception;
         }
     }
+
+    protected function createConnection(): SMTP
+    {
+        return new SMTP();
+    }
 }

tests/ProviderClient/GenericProviderClientTest.php

@@ -0,0 +1,100 @@
+<?php
+
+declare(strict_types=1);
+
+namespace AssoConnect\SmtpToolbox\Tests\ProviderClient;
+
+use AssoConnect\SmtpToolbox\ProviderClient\GenericProviderClient;
+use AssoConnect\SmtpToolbox\Resolver\BounceTypeResolver;
+use AssoConnect\SmtpToolbox\Specification\BounceIsCausedByInactiveUserSpecification;
+use AssoConnect\SmtpToolbox\Specification\BounceIsCausedByUnknownUserSpecification;
+use AssoConnect\SmtpToolbox\Specification\ExceptionComesFromTemporaryFailureSpecification;
+use PHPMailer\PHPMailer\SMTP;
+use PHPUnit\Framework\TestCase;
+use Psr\Log\NullLogger;
+
+class GenericProviderClientTest extends TestCase
+{
+    public function testConnectionUsesTheDefaultTimeout(): void
+    {
+        self::assertSame(
+            GenericProviderClient::DEFAULT_CONNECT_TIMEOUT,
+            $this->connectTimeoutUsedBy(null),
+        );
+    }
+
+    public function testConnectionUsesTheConfiguredTimeout(): void
+    {
+        self::assertSame(5, $this->connectTimeoutUsedBy(5));
+    }
+
+    private function connectTimeoutUsedBy(?int $connectTimeout): ?int
+    {
+        $connection = new class () extends SMTP {
+            private ?int $timeout = null;
+
+            /**
+             * @param string $host
+             * @param int|null $port
+             * @param int $timeout
+             * @param array<mixed> $options
+             */
+            public function connect($host, $port = null, $timeout = 30, $options = []): bool
+            {
+                $this->timeout = $timeout;
+
+                return false;
+            }
+
+            public function getConnectTimeout(): ?int
+            {
+                return $this->timeout;
+            }
+        };
+
+        $client = new class ($connection, $connectTimeout) extends GenericProviderClient {
+            public function __construct(private readonly SMTP $connection, ?int $connectTimeout)
+            {
+                $logger = new NullLogger();
+                $temporaryFailure = new ExceptionComesFromTemporaryFailureSpecification();
+                $unknownUser = new BounceIsCausedByUnknownUserSpecification();
+                $inactiveUser = new BounceIsCausedByInactiveUserSpecification();
+                $bounceTypeResolver = new BounceTypeResolver();
+
+                if (null === $connectTimeout) {
+                    parent::__construct(
+                        $logger,
+                        $temporaryFailure,
+                        $unknownUser,
+                        $inactiveUser,
+                        $bounceTypeResolver,
+                        'hello.org',
+                    );
+                } else {
+                    parent::__construct(
+                        $logger,
+                        $temporaryFailure,
+                        $unknownUser,
+                        $inactiveUser,
+                        $bounceTypeResolver,
+                        'hello.org',
+                        $connectTimeout,
+                    );
+                }
+            }
+
+            protected function createConnection(): SMTP
+            {
+                return $this->connection;
+            }
+        };
+
+        try {
+            $client->check('john@example.org', 'mx.example.org');
+        } catch (\Exception) {
+            // A refused connection always ends in an exception; only the timeout passed to connect() matters here
+        }
+
+        return $connection->getConnectTimeout();
+    }
+}