feat: email recipient whitelist

tests/EventListener/EmailRecipientWhitelistSubscriberTest.php

@@ -0,0 +1,147 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\EventListener;
+
+use App\EventListener\EmailRecipientWhitelistSubscriber;
+use PHPUnit\Framework\TestCase;
+use Psr\Log\NullLogger;
+use Symfony\Component\Mailer\Envelope;
+use Symfony\Component\Mailer\Event\MessageEvent;
+use Symfony\Component\Mime\Address;
+use Symfony\Component\Mime\Email;
+
+/**
+ * The guard that keeps staging from mailing real teamers: everything not whitelisted has to
+ * leave the envelope, and a mail with nothing left must not be sent at all.
+ */
+class EmailRecipientWhitelistSubscriberTest extends TestCase
+{
+    public function testKeepsEnvelopeUntouchedWhenEveryRecipientIsWhitelisted(): void
+    {
+        $event = $this->event(['[email protected]', '[email protected]']);
+
+        $this->subscriber(['.*@ep-reisen\.de', 'qa@example\.com'])->onMessage($event);
+
+        self::assertFalse($event->isRejected());
+        self::assertSame(
+            ['[email protected]', '[email protected]'],
+            $this->addresses($event)
+        );
+    }
+
+    public function testStripsTheRecipientsThatAreNotWhitelisted(): void
+    {
+        $event = $this->event(['[email protected]', '[email protected]', '[email protected]']);
+
+        $this->subscriber(['.*@ep-reisen\.de'])->onMessage($event);
+
+        self::assertFalse($event->isRejected());
+        self::assertSame(['[email protected]'], $this->addresses($event));
+    }
+
+    public function testRejectsTheMailWhenNoRecipientIsWhitelisted(): void
+    {
+        $event = $this->event(['[email protected]', '[email protected]']);
+
+        $this->subscriber(['.*@ep-reisen\.de'])->onMessage($event);
+
+        self::assertTrue($event->isRejected());
+    }
+
+    public function testDoesNothingWithoutAWhitelist(): void
+    {
+        $event = $this->event(['[email protected]']);
+
+        $this->subscriber([])->onMessage($event);
+
+        self::assertFalse($event->isRejected());
+        self::assertSame(['[email protected]'], $this->addresses($event));
+    }
+
+    public function testPatternsAreAnchoredToTheWholeAddress(): void
+    {
+        $event = $this->event(['[email protected]']);
+
+        $this->subscriber(['.*@ep-reisen\.de'])->onMessage($event);
+
+        self::assertTrue($event->isRejected());
+    }
+
+    public function testMatchingIsCaseInsensitive(): void
+    {
+        $event = $this->event(['[email protected]']);
+
+        $this->subscriber(['.*@ep-reisen\.de'])->onMessage($event);
+
+        self::assertFalse($event->isRejected());
+        self::assertSame(['[email protected]'], $this->addresses($event));
+    }
+
+    public function testBlankPatternsAreIgnoredInsteadOfDroppingEveryMail(): void
+    {
+        $event = $this->event(['[email protected]']);
+
+        $this->subscriber([' ', '', "\t"])->onMessage($event);
+
+        self::assertFalse($event->isRejected());
+        self::assertSame(['[email protected]'], $this->addresses($event));
+    }
+
+    public function testPatternsAreTrimmed(): void
+    {
+        $event = $this->event(['[email protected]', '[email protected]']);
+
+        $this->subscriber([' .*@ep-reisen\\.de '])->onMessage($event);
+
+        self::assertFalse($event->isRejected());
+        self::assertSame(['[email protected]'], $this->addresses($event));
+    }
+
+    public function testAnInvalidPatternFailsLoudlyOnConstruction(): void
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Invalid recipient whitelist pattern ".*@ep-reisen\\.de("');
+
+        $this->subscriber(['.*@ep-reisen\\.de(']);
+    }
+
+    /**
+     * @param string[] $allowedRecipients
+     */
+    private function subscriber(array $allowedRecipients): EmailRecipientWhitelistSubscriber
+    {
+        return new EmailRecipientWhitelistSubscriber($allowedRecipients, new NullLogger());
+    }
+
+    /**
+     * @param string[] $recipients
+     */
+    private function event(array $recipients): MessageEvent
+    {
+        $email = (new Email())
+            ->from('[email protected]')
+            ->to(...$recipients)
+            ->subject('Honorarvertrag fällig')
+            ->text('...')
+        ;
+
+        return new MessageEvent(
+            $email,
+            new Envelope(new Address('[email protected]'), Address::createArray($recipients)),
+            'main'
+        );
+    }
+
+    /**
+     * @return string[]
+     */
+    private function addresses(MessageEvent $event): array
+    {
+        return array_map(
+            static fn (Address $address) => $address->getAddress(),
+            $event->getEnvelope()->getRecipients()
+        );
+    }
+}