Raise a specific exception on connection error

pp81381 · Aug 15, 2020 · cf34355 · cf34355
1 parent f1e49d2
commit cf34355
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Showing 2 changed files with 25 additions and 15 deletions.
diff --git a/rsp1570serial/connection.py b/rsp1570serial/connection.py
@@ -3,14 +3,18 @@
 import logging
 from rsp1570serial.commands import encode_command, encode_volume_direct_command
 from rsp1570serial.messages import decode_message_stream
-from serial import PARITY_NONE, STOPBITS_ONE
+from serial import PARITY_NONE, STOPBITS_ONE, SerialException
 from serial_asyncio import open_serial_connection
 import uuid
 import weakref
 
 _LOGGER = logging.getLogger(__name__)
 
 
+class RotelAmpConnConnectionError(Exception):
+    pass
+
+
 class RotelAmpConn:
     """
     Basic connection to a Rotel Amp
@@ -26,13 +30,16 @@ def __init__(self, serial_port):
 
     async def open(self):
         if not self.is_open:
-            self.reader, self.writer = await open_serial_connection(
-                url=self.serial_port,
-                baudrate=115200,
-                timeout=None,
-                parity=PARITY_NONE,
-                stopbits=STOPBITS_ONE,
-            )
+            try:
+                self.reader, self.writer = await open_serial_connection(
+                    url=self.serial_port,
+                    baudrate=115200,
+                    timeout=None,
+                    parity=PARITY_NONE,
+                    stopbits=STOPBITS_ONE,
+                )
+            except SerialException as exc:
+                raise RotelAmpConnConnectionError(str(exc)) from exc
             self.is_open = True
 
     def close(self):

diff --git a/rsp1570serial/tests/test_connection.py b/rsp1570serial/tests/test_connection.py
@@ -1,7 +1,7 @@
 import asyncio
 import aiounittest
 from contextlib import asynccontextmanager
-from rsp1570serial.connection import SharedRotelAmpConn
+from rsp1570serial.connection import SharedRotelAmpConn, RotelAmpConnConnectionError
 from rsp1570serial.emulator import (
     make_message_handler,
     create_device,
@@ -125,18 +125,21 @@ async def test_multi_clients1(self):
 
     async def test_connection_failure1(self):
         shared_conn = SharedRotelAmpConn(f"socket://:{BAD_TEST_PORT}")
-        with self.assertRaises(SerialException):
-            # Connection refused by host
+        # Connection refused by host
+        with self.assertRaises(RotelAmpConnConnectionError) as cm:
             await shared_conn.open()
+        self.assertIsInstance(cm.exception.__cause__, SerialException)
 
     async def test_connection_failure2(self):
         shared_conn = SharedRotelAmpConn(f"socket://192.168.51.1:{TEST_PORT}")
-        with self.assertRaises(SerialException):
-            # Timed out due to made up IP address
+        # Timed out due to made up IP address
+        with self.assertRaises(RotelAmpConnConnectionError) as cm:
             await shared_conn.open()
+        self.assertIsInstance(cm.exception.__cause__, SerialException)
 
     async def test_connection_failure3(self):
         shared_conn = SharedRotelAmpConn(f"socket://made_up_hostname:{TEST_PORT}")
-        with self.assertRaises(SerialException):
-            # getaddrinfo failed
+        # getaddrinfo failed
+        with self.assertRaises(RotelAmpConnConnectionError) as cm:
             await shared_conn.open()
+        self.assertIsInstance(cm.exception.__cause__, SerialException)