Merge branch 'main' into NODE-5549

Author: durran

test/integration/client-side-encryption/client_side_encryption.prose.14.decryption_events.test.ts

@@ -75,11 +75,14 @@ describe('14. Decryption Events', metadata, function () {
       keyId: keyId,
       algorithm: 'AEAD_AES_256_CBC_HMAC_SHA_512-Deterministic'
     });
-    // Copy ``ciphertext`` into a variable named ``malformedCiphertext``.
-    // Change the last byte to 0. This will produce an invalid HMAC tag.
+    // Copy ``ciphertext`` into a variable named ``malformedCiphertext``. Change the
+    // last byte to a different value. This will produce an invalid HMAC tag.
     const buffer = Buffer.from(cipherText.buffer);
-    buffer.writeInt8(0, buffer.length - 1);
+    const lastByte = buffer.readUInt8(buffer.length - 1);
+    const replacementByte = lastByte === 0 ? 1 : 0;
+    buffer.writeUInt8(replacementByte, buffer.length - 1);
     malformedCiphertext = new Binary(buffer, 6);
+
     // Create a MongoClient named ``encryptedClient`` with these ``AutoEncryptionOpts``:
     //   AutoEncryptionOpts {
     //     keyVaultNamespace: "keyvault.datakeys";