fix: Let OS select an available port when running TestInstalledAppFlow (googleapis#407)

nolanleastin · web-flow · commit 5c1a0d25eb00 · 2025-04-01T13:47:07.000-07:00
tests.unit.test_flow.TestInstalledAppFlow attempts to create a new server at the specified host:port. New server creation occasionally results in 'address already in use' because the socket will be unavailable for a period of time after the socket is closed, resulting in flaky test failures. Work around this in the tests by letting the OS pick an available port each time. Fixes googleapis#381
diff --git a/packages/google-auth-oauthlib/tests/unit/test_flow.py b/packages/google-auth-oauthlib/tests/unit/test_flow.py
@@ -18,7 +18,6 @@
 import json
 import os
 import re
-import random
 import socket
 
 import mock
@@ -251,25 +250,15 @@ def instance(self):
             CLIENT_SECRETS_INFO, scopes=self.SCOPES
         )
 
-    def is_port_in_use(self, port, host="localhost"):
-        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
-            return s.connect_ex((host, port)) == 0
-
     @pytest.fixture
     def port(self):
         # Creating a new server at the same port will result in
         # a 'Address already in use' error for a brief
         # period of time after the socket has been closed.
-        # Work around this in the tests by choosing a different port each time.
-        # https://stackoverflow.com/questions/6380057/python-binding-socket-address-already-in-use
-        random_port = -1
-        for _ in range(10):
-            random_port = random.randrange(60400, 60900)
-            if not self.is_port_in_use(random_port):
-                break
-        else:
-            raise OSError("Could not find a free port")
-        yield random_port
+        # Work around this in the tests by letting the OS pick an available port each time.
+        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+            s.bind(("localhost", 0))
+            return s.getsockname()[1]
 
     @pytest.fixture
     def socket(self, port):
