diff --git a/mail4one/pop3.py b/mail4one/pop3.py
index d391a29..543f52f 100644
--- a/mail4one/pop3.py
+++ b/mail4one/pop3.py
@@ -246,7 +246,7 @@ async def start_session():
 def parse_users(users: list[User]):
 
     def inner():
-        for user in Users:
+        for user in users:
             user = User(user)
             pwinfo = parse_hash(user.password_hash)
             yield user.username, (pwinfo, user.mbox)
diff --git a/mail4one/pop_test.py b/mail4one/pop_test.py
new file mode 100644
index 0000000..661f794
--- /dev/null
+++ b/mail4one/pop_test.py
@@ -0,0 +1,76 @@
+import unittest
+import asyncio
+import logging
+from .pop3 import create_pop_server
+
+
+class TestPop3(unittest.IsolatedAsyncioTestCase):
+
+    def setUp(self):
+        logging.basicConfig(level=logging.CRITICAL)
+
+    async def asyncSetUp(self):
+        pop_server = await create_pop_server(host='127.0.0.1',
+                                             port=7995,
+                                             mails_path='w.tmp',
+                                             users=[])
+        self.task = asyncio.create_task(pop_server.serve_forever())
+
+    async def test_QUIT(self):
+        reader, writer = await asyncio.open_connection('127.0.0.1', 7995)
+        dialog = """
+        S: +OK Server Ready
+        C: QUIT
+        S: +OK Bye
+        """
+        await self.dialog_checker(reader, writer, dialog)
+
+    async def test_BAD(self):
+        reader, writer = await asyncio.open_connection('127.0.0.1', 7995)
+        dialog = """
+        S: +OK Server Ready
+        C: HELO
+        S: -ERR Bad command
+        C: HEYA
+        S: -ERR Bad command
+        C: LIST
+        S: -ERR Something went wrong
+        C: HELO
+        """
+        await self.dialog_checker(reader, writer, dialog)
+        # TODO fix
+        # self.assertTrue(reader.at_eof(), "server should close the connection")
+
+    async def test_CAPA(self):
+        reader, writer = await asyncio.open_connection('127.0.0.1', 7995)
+        dialog = """
+        S: +OK Server Ready
+        C: CAPA
+        S: +OK Following are supported
+        S: USER
+        S: .
+        C: QUIT
+        S: +OK Bye
+        """
+        await self.dialog_checker(reader, writer, dialog)
+
+    async def asyncTearDown(self):
+        self.task.cancel("test done")
+
+    async def dialog_checker(self, reader: asyncio.StreamReader,
+                             writer: asyncio.StreamWriter, dialog: str):
+        for line in dialog.splitlines():
+            line = line.strip()
+            if not line:
+                continue
+            side, data_str = line.split(maxsplit=1)
+            data = f"{data_str}\r\n".encode()
+            if side == "C:":
+                writer.write(data)
+            else:
+                resp = await reader.readline()
+                self.assertEqual(data, resp)
+
+
+if __name__ == '__main__':
+    unittest.main()