Refactor tests to use assertions consistently and improve type hints

* Initial plan

* Address review feedback: Kafka SSL context, SIGHUP handler safety, test formatting

Co-authored-by: seanthegeek <44679+seanthegeek@users.noreply.github.com>
Agent-Logs-Url: https://github.com/domainaware/parsedmarc/sessions/8f2fd48f-32a4-4258-9a89-06f7c7ac29bf

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: seanthegeek <44679+seanthegeek@users.noreply.github.com>

tests.py

@@ -202,7 +202,9 @@ class Test(unittest.TestCase):
                     sample_content, offline=OFFLINE_MODE
                 )
                 assert email_result["report_type"] == "forensic"
-            result = parsedmarc.parse_report_file(sample_path, offline=OFFLINE_MODE)
+            result = parsedmarc.parse_report_file(
+                sample_path, offline=OFFLINE_MODE
+            )
             assert result["report_type"] == "forensic"
             parsedmarc.parsed_forensic_reports_to_csv(result["report"])
             print("Passed!")
@@ -215,7 +217,9 @@ class Test(unittest.TestCase):
             if os.path.isdir(sample_path):
                 continue
             print("Testing {0}: ".format(sample_path), end="")
-            result = parsedmarc.parse_report_file(sample_path, offline=OFFLINE_MODE)
+            result = parsedmarc.parse_report_file(
+                sample_path, offline=OFFLINE_MODE
+            )
             assert result["report_type"] == "smtp_tls"
             parsedmarc.parsed_smtp_tls_reports_to_csv(result["report"])
             print("Passed!")
@@ -1291,9 +1295,7 @@ class TestMailboxWatchSince(unittest.TestCase):
         ) as mocked:
             with self.assertRaises(_BreakLoop):
                 parsedmarc.watch_inbox(
-                    mailbox_connection=cast(
-                        parsedmarc.MailboxConnection, mailbox_connection
-                    ),
+                    mailbox_connection=cast(parsedmarc.MailboxConnection, mailbox_connection),
                     callback=callback,
                     check_timeout=1,
                     batch_size=10,