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Meister-Eder/tests/test_email_loop_prevention.py
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Claude 491c2d3495 test: add tests for email loop prevention 
Add tests/test_email_loop_prevention.py (47 tests) covering:
- detect_automated_message(): sender patterns (mailer-daemon, postmaster,
  noreply, …), RFC headers (Auto-Submitted, X-Auto-Response-Suppress,
  multipart/report, X-Loop, Precedence), subject heuristics (German and
  English bounce/OOO phrases), and negative cases for normal senders
- EmailAgent.handle_automated_message(): state creation, loop_escalated
  flag, one-shot admin alert, silent drop on repeat, notifier failure safety
- EmailAgent.process_message() message-count cap: at-limit still processes,
  over-limit returns "", escalation called once, duplicate prevention,
  notifier failure safety, constant value assertion
- AdminNotifier.notify_loop_escalation(): SMTP dispatch, [WARNUNG] subject,
  body content, no-CC guard, no-SMTP dev-mode guard

Add TestConversationStateLoopEscalated to test_models.py (5 tests):
default value, to_dict inclusion, True round-trip, from_dict backward
compatibility with persisted conversations missing the key.

All 168 tests pass.

https://claude.ai/code/session_01KwvR5hDPjSuJg4kvw5b5e5
2026-02-26 21:03:01 +00:00

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"""Tests for email loop prevention.
Covers three layers:
- detect_automated_message() — header-based bounce/automated sender detection
- EmailAgent.handle_automated_message() — state tracking, one-shot admin alert
- EmailAgent.process_message() — hard message-count cap (MAX_USER_MESSAGES)
- AdminNotifier.notify_loop_escalation() — escalation email dispatch
"""
import email
import json
import pytest
from unittest.mock import MagicMock, patch
from src.channels.email_channel import detect_automated_message
from src.agent.core import EmailAgent, MAX_USER_MESSAGES
from src.models.conversation import ConversationState, ChatMessage
from src.notifications.notifier import AdminNotifier
# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
def _decode_body(msg_str: str) -> str:
"""Extract the decoded plain-text body from a raw MIME message string."""
parsed = email.message_from_string(msg_str)
if parsed.is_multipart():
for part in parsed.walk():
if part.get_content_type() == "text/plain":
payload = part.get_payload(decode=True)
if payload:
return payload.decode(part.get_content_charset() or "utf-8")
payload = parsed.get_payload(decode=True)
return payload.decode(parsed.get_content_charset() or "utf-8") if payload else ""
def _make_msg(
from_addr: str = "parent@example.com",
subject: str = "Hallo",
extra_headers: dict | None = None,
content_type: str = "text/plain",
) -> email.message.Message:
"""Build a minimal parsed email.message.Message for testing detect_automated_message."""
raw = (
f"From: {from_addr}\r\n"
f"Subject: {subject}\r\n"
f"Content-Type: {content_type}\r\n"
)
for key, value in (extra_headers or {}).items():
raw += f"{key}: {value}\r\n"
raw += "\r\nBody text"
return email.message_from_string(raw)
def _state_with_n_user_messages(n: int, email_addr: str = "loop@example.com") -> ConversationState:
"""Return a ConversationState that already has *n* user messages in its history."""
state = ConversationState(
conversation_id=email_addr,
parent_email=email_addr,
)
for i in range(n):
state.messages.append(ChatMessage(role="user", content=f"Message {i + 1}"))
state.messages.append(ChatMessage(role="assistant", content=f"Reply {i + 1}"))
return state
VALID_LLM_REPLY = json.dumps({
"reply": "Wie heisst dein Kind?",
"updates": {},
"next_step": "child_name",
"registration_complete": False,
"language": "de",
})
# ---------------------------------------------------------------------------
# Fixtures
# ---------------------------------------------------------------------------
@pytest.fixture
def mock_kb():
kb = MagicMock()
kb.get_all.return_value = "# FAQ\nSome content."
return kb
@pytest.fixture
def mock_store():
store = MagicMock()
store.load.return_value = None
store.save_registration.return_value = ("loop@example.com", 1)
return store
@pytest.fixture
def mock_notifier():
return MagicMock()
@pytest.fixture
def agent(mock_kb, mock_store, mock_notifier):
return EmailAgent(
model="anthropic/claude-opus-4-6",
kb=mock_kb,
store=mock_store,
notifier=mock_notifier,
)
@pytest.fixture
def notifier():
return AdminNotifier(
smtp_host="smtp.example.com",
smtp_port=587,
username="agent@example.com",
password="secret",
use_tls=True,
from_email="agent@example.com",
indoor_email="andrea@example.com",
outdoor_email="barbara@example.com",
cc_emails=["markus@example.com"],
)
@pytest.fixture
def notifier_no_cc():
"""Notifier without any CC recipients — simulates missing ADMIN_EMAIL_CC."""
return AdminNotifier(
smtp_host="smtp.example.com",
smtp_port=587,
username="agent@example.com",
password="secret",
use_tls=True,
from_email="agent@example.com",
cc_emails=[],
)
@pytest.fixture
def notifier_no_smtp():
"""Notifier in dev mode (no SMTP host)."""
return AdminNotifier(
smtp_host="",
smtp_port=587,
username="",
password="",
from_email="agent@example.com",
cc_emails=["markus@example.com"],
)
# ---------------------------------------------------------------------------
# detect_automated_message — sender address patterns
# ---------------------------------------------------------------------------
class TestDetectAutomatedMessageBySender:
def test_mailer_daemon_is_automated(self):
msg = _make_msg(from_addr="MAILER-DAEMON@tacitus2.sui-inter.net")
is_auto, reason = detect_automated_message(msg, "MAILER-DAEMON@tacitus2.sui-inter.net")
assert is_auto is True
assert reason != ""
def test_mailer_daemon_lowercase_is_automated(self):
msg = _make_msg(from_addr="mailer-daemon@example.com")
is_auto, _ = detect_automated_message(msg, "mailer-daemon@example.com")
assert is_auto is True
def test_postmaster_is_automated(self):
msg = _make_msg(from_addr="postmaster@example.com")
is_auto, _ = detect_automated_message(msg, "postmaster@example.com")
assert is_auto is True
def test_noreply_is_automated(self):
msg = _make_msg(from_addr="noreply@example.com")
is_auto, _ = detect_automated_message(msg, "noreply@example.com")
assert is_auto is True
def test_no_reply_hyphen_is_automated(self):
msg = _make_msg(from_addr="no-reply@example.com")
is_auto, _ = detect_automated_message(msg, "no-reply@example.com")
assert is_auto is True
def test_donotreply_is_automated(self):
msg = _make_msg(from_addr="donotreply@example.com")
is_auto, _ = detect_automated_message(msg, "donotreply@example.com")
assert is_auto is True
def test_bounce_is_automated(self):
msg = _make_msg(from_addr="bounce@example.com")
is_auto, _ = detect_automated_message(msg, "bounce@example.com")
assert is_auto is True
def test_normal_parent_email_is_not_automated(self):
msg = _make_msg(from_addr="anna.muster@example.com")
is_auto, reason = detect_automated_message(msg, "anna.muster@example.com")
assert is_auto is False
assert reason == ""
def test_reason_string_mentions_sender(self):
msg = _make_msg(from_addr="MAILER-DAEMON@tacitus2.sui-inter.net")
_, reason = detect_automated_message(msg, "MAILER-DAEMON@tacitus2.sui-inter.net")
assert "MAILER-DAEMON@tacitus2.sui-inter.net" in reason
# ---------------------------------------------------------------------------
# detect_automated_message — RFC / header signals
# ---------------------------------------------------------------------------
class TestDetectAutomatedMessageByHeaders:
def test_auto_submitted_auto_replied(self):
msg = _make_msg(extra_headers={"Auto-Submitted": "auto-replied"})
is_auto, reason = detect_automated_message(msg, "someone@example.com")
assert is_auto is True
assert "auto-replied" in reason
def test_auto_submitted_auto_generated(self):
msg = _make_msg(extra_headers={"Auto-Submitted": "auto-generated"})
is_auto, _ = detect_automated_message(msg, "someone@example.com")
assert is_auto is True
def test_auto_submitted_no_is_not_automated(self):
"""Auto-Submitted: no means the message was composed by a human."""
msg = _make_msg(extra_headers={"Auto-Submitted": "no"})
is_auto, _ = detect_automated_message(msg, "parent@example.com")
assert is_auto is False
def test_x_auto_response_suppress_is_automated(self):
msg = _make_msg(extra_headers={"X-Auto-Response-Suppress": "All"})
is_auto, reason = detect_automated_message(msg, "someone@example.com")
assert is_auto is True
assert "X-Auto-Response-Suppress" in reason
def test_multipart_report_content_type_is_automated(self):
msg = _make_msg(content_type="multipart/report")
is_auto, reason = detect_automated_message(msg, "system@example.com")
assert is_auto is True
assert "multipart/report" in reason
def test_x_loop_header_is_automated(self):
msg = _make_msg(extra_headers={"X-Loop": "spielgruppen@familien-verein.ch"})
is_auto, reason = detect_automated_message(msg, "someone@example.com")
assert is_auto is True
assert "X-Loop" in reason
def test_precedence_bulk_is_automated(self):
msg = _make_msg(extra_headers={"Precedence": "bulk"})
is_auto, reason = detect_automated_message(msg, "list@example.com")
assert is_auto is True
assert "bulk" in reason
def test_precedence_junk_is_automated(self):
msg = _make_msg(extra_headers={"Precedence": "junk"})
is_auto, _ = detect_automated_message(msg, "spam@example.com")
assert is_auto is True
def test_precedence_list_is_not_automated(self):
"""Mailing list messages (Precedence: list) are not considered automated."""
msg = _make_msg(extra_headers={"Precedence": "list"})
is_auto, _ = detect_automated_message(msg, "newsletter@example.com")
assert is_auto is False
# ---------------------------------------------------------------------------
# detect_automated_message — subject heuristics
# ---------------------------------------------------------------------------
class TestDetectAutomatedMessageBySubject:
def test_undelivered_mail_returned_to_sender(self):
msg = _make_msg(subject="Undelivered Mail Returned to Sender")
is_auto, reason = detect_automated_message(msg, "mailer@example.com")
# Caught by sender pattern first, but subject pattern must also flag it
# Test that a neutral sender + bounce subject is still flagged
msg2 = _make_msg(
from_addr="delivery@isp.example.com",
subject="Undelivered Mail Returned to Sender",
)
is_auto2, _ = detect_automated_message(msg2, "delivery@isp.example.com")
assert is_auto2 is True
def test_delivery_failed_subject(self):
msg = _make_msg(
from_addr="system@isp.example.com",
subject="Mail Delivery Failed",
)
is_auto, _ = detect_automated_message(msg, "system@isp.example.com")
assert is_auto is True
def test_out_of_office_subject(self):
msg = _make_msg(
from_addr="colleague@example.com",
subject="Out of Office: Re: Anmeldung",
)
is_auto, _ = detect_automated_message(msg, "colleague@example.com")
assert is_auto is True
def test_abwesenheitsnotiz_subject(self):
msg = _make_msg(
from_addr="colleague@example.com",
subject="Abwesenheitsnotiz: Anmeldung",
)
is_auto, _ = detect_automated_message(msg, "colleague@example.com")
assert is_auto is True
def test_automatische_antwort_subject(self):
msg = _make_msg(
from_addr="colleague@example.com",
subject="Automatische Antwort: Ihre Anfrage",
)
is_auto, _ = detect_automated_message(msg, "colleague@example.com")
assert is_auto is True
def test_normal_registration_subject_is_not_automated(self):
msg = _make_msg(
from_addr="parent@example.com",
subject="Anmeldung meines Kindes",
)
is_auto, _ = detect_automated_message(msg, "parent@example.com")
assert is_auto is False
def test_case_insensitive_subject_matching(self):
msg = _make_msg(
from_addr="system@isp.example.com",
subject="UNDELIVERED MAIL RETURNED TO SENDER",
)
is_auto, _ = detect_automated_message(msg, "system@isp.example.com")
assert is_auto is True
# ---------------------------------------------------------------------------
# EmailAgent.handle_automated_message — state and escalation
# ---------------------------------------------------------------------------
class TestHandleAutomatedMessage:
def test_sets_loop_escalated_on_state(self, agent, mock_store):
"""Calling handle_automated_message marks loop_escalated = True in state."""
agent.handle_automated_message(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
subject="Undelivered Mail Returned to Sender",
reason="sender matches automated address pattern",
)
saved_state = mock_store.save.call_args[0][0]
assert saved_state.loop_escalated is True
def test_calls_notify_loop_escalation(self, agent, mock_notifier):
"""Admin is notified once on the first automated message."""
agent.handle_automated_message(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
subject="Undelivered Mail Returned to Sender",
reason="sender matches automated address pattern",
)
mock_notifier.notify_loop_escalation.assert_called_once()
def test_notify_called_with_correct_sender(self, agent, mock_notifier):
agent.handle_automated_message(
sender_email="MAILER-DAEMON@tacitus2.sui-inter.net",
subject="Bounce",
reason="sender match",
)
call_kwargs = mock_notifier.notify_loop_escalation.call_args[1]
assert call_kwargs["sender_email"] == "MAILER-DAEMON@tacitus2.sui-inter.net"
def test_creates_new_state_when_none_exists(self, agent, mock_store):
"""When no prior state exists, a new ConversationState is created and saved."""
mock_store.load.return_value = None
agent.handle_automated_message(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
subject="Bounce",
reason="automated sender",
)
assert mock_store.save.called
saved_state = mock_store.save.call_args[0][0]
assert saved_state.parent_email == "mailer-daemon@tacitus2.sui-inter.net"
def test_subsequent_automated_message_dropped_silently(self, agent, mock_store, mock_notifier):
"""If loop_escalated is already True, no further notify call is made."""
existing_state = ConversationState(
conversation_id="mailer-daemon@tacitus2.sui-inter.net",
parent_email="mailer-daemon@tacitus2.sui-inter.net",
)
existing_state.loop_escalated = True
mock_store.load.return_value = existing_state
agent.handle_automated_message(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
subject="Bounce again",
reason="automated sender",
)
mock_notifier.notify_loop_escalation.assert_not_called()
def test_state_still_saved_when_already_escalated(self, agent, mock_store, mock_notifier):
"""Even when already escalated, last_activity is updated and state is persisted."""
existing_state = ConversationState(
conversation_id="mailer-daemon@tacitus2.sui-inter.net",
parent_email="mailer-daemon@tacitus2.sui-inter.net",
)
existing_state.loop_escalated = True
mock_store.load.return_value = existing_state
agent.handle_automated_message(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
subject="Bounce again",
reason="automated sender",
)
assert mock_store.save.called
def test_notifier_failure_does_not_propagate(self, agent, mock_store, mock_notifier):
"""A failing notifier must not crash the agent — the state is still saved."""
mock_notifier.notify_loop_escalation.side_effect = RuntimeError("SMTP error")
# Should not raise
agent.handle_automated_message(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
subject="Bounce",
reason="automated sender",
)
assert mock_store.save.called
def test_inbound_message_id_stored(self, agent, mock_store):
"""The inbound Message-ID is persisted for reply-threading purposes."""
agent.handle_automated_message(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
subject="Bounce",
reason="automated sender",
inbound_message_id="<abc123@tacitus2.sui-inter.net>",
)
saved_state = mock_store.save.call_args[0][0]
assert saved_state.last_inbound_message_id == "<abc123@tacitus2.sui-inter.net>"
# ---------------------------------------------------------------------------
# EmailAgent.process_message — hard message-count cap
# ---------------------------------------------------------------------------
class TestProcessMessageCountCap:
def test_at_limit_message_still_processed(self, agent, mock_store):
"""A conversation with exactly MAX_USER_MESSAGES messages is still replied to."""
state = _state_with_n_user_messages(MAX_USER_MESSAGES - 1)
mock_store.load.return_value = state
with patch("src.llm.complete", return_value=VALID_LLM_REPLY):
reply = agent.process_message("loop@example.com", "Another message")
assert reply == "Wie heisst dein Kind?"
def test_over_limit_returns_empty_string(self, agent, mock_store):
"""The 21st user message triggers the cap and returns an empty reply."""
state = _state_with_n_user_messages(MAX_USER_MESSAGES)
mock_store.load.return_value = state
with patch("src.llm.complete", return_value=VALID_LLM_REPLY) as mock_llm:
reply = agent.process_message("loop@example.com", "One more message")
assert reply == ""
mock_llm.assert_not_called()
def test_over_limit_sets_loop_escalated(self, agent, mock_store):
"""Hitting the cap marks loop_escalated = True in the persisted state."""
state = _state_with_n_user_messages(MAX_USER_MESSAGES)
mock_store.load.return_value = state
with patch("src.llm.complete", return_value=VALID_LLM_REPLY):
agent.process_message("loop@example.com", "One more message")
saved_state = mock_store.save.call_args[0][0]
assert saved_state.loop_escalated is True
def test_over_limit_calls_notify_loop_escalation(self, agent, mock_store, mock_notifier):
"""Hitting the cap triggers one admin escalation notification."""
state = _state_with_n_user_messages(MAX_USER_MESSAGES)
mock_store.load.return_value = state
with patch("src.llm.complete", return_value=VALID_LLM_REPLY):
agent.process_message("loop@example.com", "One more message")
mock_notifier.notify_loop_escalation.assert_called_once()
def test_over_limit_no_duplicate_notification_when_already_escalated(
self, agent, mock_store, mock_notifier
):
"""If loop_escalated is already True, no second notification is sent."""
state = _state_with_n_user_messages(MAX_USER_MESSAGES)
state.loop_escalated = True
mock_store.load.return_value = state
with patch("src.llm.complete", return_value=VALID_LLM_REPLY):
agent.process_message("loop@example.com", "Yet another message")
mock_notifier.notify_loop_escalation.assert_not_called()
def test_over_limit_notify_failure_does_not_propagate(self, agent, mock_store, mock_notifier):
"""If the notifier raises, the cap still returns '' without crashing."""
mock_notifier.notify_loop_escalation.side_effect = RuntimeError("SMTP down")
state = _state_with_n_user_messages(MAX_USER_MESSAGES)
mock_store.load.return_value = state
with patch("src.llm.complete", return_value=VALID_LLM_REPLY):
reply = agent.process_message("loop@example.com", "One more message")
assert reply == ""
def test_max_user_messages_constant_is_twenty(self):
"""The agreed-upon limit from the spec is 20 inbound messages."""
assert MAX_USER_MESSAGES == 20
# ---------------------------------------------------------------------------
# AdminNotifier.notify_loop_escalation — SMTP dispatch
# ---------------------------------------------------------------------------
class TestNotifyLoopEscalation:
def test_sends_email_to_cc_recipients(self, notifier, mocker):
"""The escalation alert is sent to the admin CC address list."""
mock_smtp_cls = mocker.patch("smtplib.SMTP")
mock_server = mock_smtp_cls.return_value
notifier.notify_loop_escalation(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
conversation_id="mailer-daemon@tacitus2.sui-inter.net",
reason="sender matches automated address pattern",
message_count=5,
)
mock_server.sendmail.assert_called_once()
call_args = mock_server.sendmail.call_args
recipients = call_args[0][1]
assert "markus@example.com" in recipients
def test_subject_contains_warnung_tag(self, notifier, mocker):
"""Subject must start with [WARNUNG] for easy filtering in the admin inbox."""
mock_smtp_cls = mocker.patch("smtplib.SMTP")
captured = {}
def fake_sendmail(from_, to_, msg_str):
captured["msg"] = msg_str
mock_smtp_cls.return_value.sendmail.side_effect = fake_sendmail
notifier.notify_loop_escalation(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
conversation_id="mailer-daemon@tacitus2.sui-inter.net",
reason="automated sender",
message_count=3,
)
import email as email_mod
from email.header import decode_header
parsed = email_mod.message_from_string(captured["msg"])
raw_subject = parsed.get("Subject", "")
parts = decode_header(raw_subject)
subject = "".join(
chunk.decode(enc or "utf-8") if isinstance(chunk, bytes) else chunk
for chunk, enc in parts
)
assert "[WARNUNG]" in subject
def test_subject_contains_sender_address(self, notifier, mocker):
"""The sender address appears in the subject for quick identification."""
mock_smtp_cls = mocker.patch("smtplib.SMTP")
captured = {}
def fake_sendmail(from_, to_, msg_str):
captured["msg"] = msg_str
mock_smtp_cls.return_value.sendmail.side_effect = fake_sendmail
notifier.notify_loop_escalation(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
conversation_id="mailer-daemon@tacitus2.sui-inter.net",
reason="automated sender",
message_count=3,
)
assert "mailer-daemon@tacitus2.sui-inter.net" in captured["msg"]
def test_body_contains_reason(self, notifier, mocker):
"""The email body includes the specific detection reason."""
mock_smtp_cls = mocker.patch("smtplib.SMTP")
captured = {}
def fake_sendmail(from_, to_, msg_str):
captured["msg"] = msg_str
mock_smtp_cls.return_value.sendmail.side_effect = fake_sendmail
notifier.notify_loop_escalation(
sender_email="test@example.com",
conversation_id="test@example.com",
reason="Content-Type: multipart/report (delivery status notification)",
message_count=7,
)
body = _decode_body(captured["msg"])
assert "multipart/report" in body
def test_body_contains_message_count(self, notifier, mocker):
"""The email body reports the number of messages exchanged."""
mock_smtp_cls = mocker.patch("smtplib.SMTP")
captured = {}
def fake_sendmail(from_, to_, msg_str):
captured["msg"] = msg_str
mock_smtp_cls.return_value.sendmail.side_effect = fake_sendmail
notifier.notify_loop_escalation(
sender_email="test@example.com",
conversation_id="test@example.com",
reason="automated sender",
message_count=12,
)
body = _decode_body(captured["msg"])
assert "12" in body
def test_no_cc_emails_skips_smtp(self, notifier_no_cc, mocker):
"""When no admin CC email is configured, no SMTP connection is made."""
mock_smtp_cls = mocker.patch("smtplib.SMTP")
notifier_no_cc.notify_loop_escalation(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
conversation_id="mailer-daemon@tacitus2.sui-inter.net",
reason="automated sender",
message_count=3,
)
mock_smtp_cls.assert_not_called()
def test_no_smtp_host_skips_send(self, notifier_no_smtp, mocker):
"""Dev mode (no SMTP host): email is logged but not dispatched."""
mock_smtp_cls = mocker.patch("smtplib.SMTP")
notifier_no_smtp.notify_loop_escalation(
sender_email="mailer-daemon@tacitus2.sui-inter.net",
conversation_id="mailer-daemon@tacitus2.sui-inter.net",
reason="automated sender",
message_count=3,
)
mock_smtp_cls.assert_not_called()
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