Fix mailbox name as only numbers

docker-compose.yml

@@ -6,7 +6,7 @@ services:
     container_name: php-imap
     volumes:
       - .:/project_orig
-    command: bash -c "wait-for-it.sh imap.server:993 && cp -dpr /project_orig /project && cd /project && composer install && vendor/bin/phpunit"
+    command: bash -c "wait-for-it.sh imap.server:993 && cp -dpr /project_orig /project && cd /project && composer install && vendor/bin/phpunit --stop-on-failure"
     environment:
       - IMAP_SERVER_NAME=imap.server
       - IMAP_SERVER_PORT=993

src/Connection.php

@@ -92,7 +92,7 @@ public function getMailboxes(): array
         if (null === $this->mailboxes) {
             $this->mailboxes = [];
             foreach ($this->mailboxNames as $mailboxName => $mailboxInfo) {
-                $this->mailboxes[$mailboxName] = $this->getMailbox($mailboxName);
+                $this->mailboxes[(string) $mailboxName] = $this->getMailbox((string) $mailboxName);
             }
         }
 

tests/ConnectionTest.php

@@ -134,4 +134,15 @@ public function testGetInvalidMailbox()
         $this->expectException(MailboxDoesNotExistException::class);
         $this->getConnection()->getMailbox('does-not-exist');
     }
+
+    public function testNumericMailbox()
+    {
+        $number = (string) \mt_rand(100, 999);
+        $conn = $this->getConnection();
+        $mailbox = $conn->createMailbox($number);
+
+        $mailboxes = $conn->getMailboxes();
+
+        static::assertArrayHasKey($number, $mailboxes);
+    }
 }