chore(ses): create unit tests for drop spam handler (#27769)

This PR adds unit tests for the SES drop spam handler. Specifically, the unit tests verify that spam will be dropped under the following conditions:

1. SPF verdict is `FAIL`
2. DKIM verdict is `FAIL`
3. Spam verdict is `FAIL`
4. Virus verdict is `FAIL`

An additional unit test was added to ensure that null is returned if all the above verdicts are not `FAIL`.

Closes #27726

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: colifran

packages/aws-cdk-lib/aws-ses/test/drop-spam-handler/drop-spam-handler.test.ts

@@ -0,0 +1,117 @@
+import { handler } from '../../lib/drop-spam-handler/index';
+
+describe('handler', () => {
+  test.each(['spf', 'dkim', 'spam', 'virus'])('drop spam when %s status is FAIL', async (key) => {
+    const sesEvent = createSesEvent({ [key]: { status: 'FAIL' } });
+    const response = await handler(sesEvent);
+    expect(response).toEqual({ disposition: 'STOP_RULE_SET' });
+  });
+
+  test('all spam checks pass', async () => {
+    const sesEvent = createSesEvent();
+    const response = await handler(sesEvent);
+    expect(response).toBe(null);
+  });
+});
+
+interface Verdicts {
+  spam?: AWSLambda.SESReceiptStatus,
+  virus?: AWSLambda.SESReceiptStatus,
+  spf?: AWSLambda.SESReceiptStatus,
+  dkim?: AWSLambda.SESReceiptStatus,
+  dmarc?: AWSLambda.SESReceiptStatus,
+}
+
+function createSesEvent(verdicts: Verdicts = {}) {
+  return {
+    Records: [{
+      eventSource: 'aws:sns',
+      eventVersion: '1.0',
+      ses: {
+        mail: {
+          timestamp: '2023-10-30T20:32:33.936Z',
+          source: '[email protected]',
+          messageId: 'd6iitobk75ur44p8kdnnp7g2n800',
+          destination: ['[email protected]'],
+          headersTruncated: false,
+          headers: [
+            {
+              name: 'Return-Path',
+              value: '<0000014fbe1c09cf-7cb9f704-7531-4e53-89a1-5fa9744f5eb6-000000@amazonses.com>',
+            },
+            {
+              name: 'Received',
+              value: 'from a9-183.smtp-out.amazonses.com (a9-183.smtp-out.amazonses.com [54.240.9.183]) by inbound-smtp.us-east-1.amazonaws.com with SMTP id d6iitobk75ur44p8kdnnp7g2n800 for [email protected]; Mon, 30 Oct 2023 20:32:33 +0000 (UTC)',
+            },
+            {
+              name: 'DKIM-Signature',
+              value: 'v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1442003552; h=From:To:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding:Date:Message-ID:Feedback-ID; bh=DWr3IOmYWoXCA9ARqGC/UaODfghffiwFNRIb2Mckyt4=; b=p4ukUDSFqhqiub+zPR0DW1kp7oJZakrzupr6LBe6sUuvqpBkig56UzUwc29rFbJF hlX3Ov7DeYVNoN38stqwsF8ivcajXpQsXRC1cW9z8x875J041rClAjV7EGbLmudVpPX 4hHst1XPyX5wmgdHIhmUuh8oZKpVqGi6bHGzzf7g=',
+            },
+            {
+              name: 'From',
+              value: '[email protected]',
+            },
+            {
+              name: 'To',
+              value: '[email protected]',
+            },
+            {
+              name: 'Subject',
+              value: 'Example subject',
+            },
+            {
+              name: 'MIME-Version',
+              value: '1.0',
+            },
+            {
+              name: 'Content-Type',
+              value: 'text/plain; charset=UTF-8',
+            },
+            {
+              name: 'Content-Transfer-Encoding',
+              value: '7bit',
+            },
+            {
+              name: 'Date',
+              value: 'Mon, 30 Oct 2023 20:32:32 +0000',
+            },
+            {
+              name: 'Message-ID',
+              value: '<[email protected]>',
+            },
+            {
+              name: 'X-SES-Outgoing',
+              value: '2023.10.30-54.240.9.183',
+            },
+            {
+              name: 'Feedback-ID',
+              value: '1.us-east-1.Krv2FKpFdWV+KUYw3Qd6wcpPJ4Sv/pOPpEPSHn2u2o4=:AmazonSES',
+            },
+          ],
+          commonHeaders: {
+            returnPath: '0000014fbe1c09cf-7cb9f704-7531-4e53-89a1-5fa9744f5eb6-000000@amazonses.com',
+            from: ['[email protected]'],
+            date: 'Mon, 30 Oct 2023 20:32:32 +0000',
+            to: ['[email protected]'],
+            messageId: '<[email protected]>',
+            subject: 'Example subject',
+          },
+        },
+        receipt: {
+          timestamp: '2023-10-30T20:32:33.936Z',
+          processingTimeMillis: 300,
+          recipients: ['[email protected]'],
+          spamVerdict: verdicts.spam ?? { status: 'PASS' },
+          virusVerdict: verdicts.virus ?? { status: 'PASS' },
+          spfVerdict: verdicts.spf ?? { status: 'PASS' },
+          dkimVerdict: verdicts.dkim ?? { status: 'PASS' },
+          dmarcVerdict: verdicts.dmarc ?? { status: 'PASS' },
+          action: {
+            type: 'SNS',
+            topicArn: 'arn:aws:sns:us-east-1:012345678912:example-topic',
+          },
+        },
+      },
+    }],
+  } as unknown as AWSLambda.SESEvent;
+}