feat: add Postfix/pneumatube container rig with live recipient rejection

tests/test_lookup_server.py

@@ -0,0 +1,54 @@
+import asyncio
+from types import SimpleNamespace
+from urllib.parse import unquote
+
+import pytest
+
+from pneumatube.lookup_server import _lookup
+
+
+class _StubBridge:
+    def __init__(self, known):
+        self.known = known
+
+    def user_exists(self, username):
+        if username == "broken":
+            return None
+        return username in self.known
+
+
+class _InlineWorker:
+    async def run(self, fn, *args):
+        return fn(*args)
+
+
+def _config():
+    return SimpleNamespace(email_domain="gateway.example")
+
+
+def test_lookup_known_user_returns_ok():
+    bridge = _StubBridge({"alice"})
+    reply = asyncio.run(_lookup(bridge, _InlineWorker(), _config(), "alice@gateway.example"))
+    code, _, text = reply.partition(" ")
+    assert code == "200"
+    assert unquote(text) == "OK"
+
+
+def test_lookup_unknown_user_returns_reject_action():
+    bridge = _StubBridge({"alice"})
+    reply = asyncio.run(_lookup(bridge, _InlineWorker(), _config(), "nobody@gateway.example"))
+    code, _, text = reply.partition(" ")
+    assert code == "200"
+    assert unquote(text) == "550 5.1.1 no such user"
+
+
+def test_lookup_resolve_failure_is_temporary():
+    bridge = _StubBridge({"alice"})
+    reply = asyncio.run(_lookup(bridge, _InlineWorker(), _config(), "broken@gateway.example"))
+    assert reply.startswith("400 ")
+
+
+def test_lookup_other_domain_has_no_opinion():
+    bridge = _StubBridge({"alice"})
+    reply = asyncio.run(_lookup(bridge, _InlineWorker(), _config(), "alice@other.example"))
+    assert reply == "500 not found"