Ensure port used by process tests is unused

When running in a loop catalyst occasionally runs into... OSError: Process terminated: Failed to bind one of the listener ports. https://trac.torproject.org/projects/tor/ticket/22902 First guess is that maybe multiple tests pick the same random port, or something that's coincidently being used by the system. Tried to use socket's connect_ex() for this... https://stackoverflow.com/questions/19196105/python-how-to-check-if-a-network-port-is-open-on-linux But doing so causes exactly the binding failures we're attempting to avoid (even with a sleep after closing). Weird. Just checking for process instead.

Ensure port used by process tests is unused
d3781001 · Damian Johnson · 7901ff11 · d3781001
Commit d3781001 authored Jul 14, 2017 by Damian Johnson
--- a/test/integ/process.py
+++ b/test/integ/process.py
@@ -2,6 +2,8 @@
 Tests the stem.process functions with various use cases.
 """

+from __future__ import absolute_import
+
 import binascii
 import hashlib
 import os
@@ -45,7 +47,11 @@ DataDirectory %s


 def random_port():
-  return str(random.randint(1024, 65535))
+  while True:
+    port = random.randint(1024, 65535)
+
+    if stem.util.system.pid_by_port(port) is None:
+      return str(port)


 @contextmanager
@@ -552,8 +558,8 @@ class TestProcess(unittest.TestCase):
      except OSError:
        runtime = time.time() - start_time

-        if not (runtime > 0.05 and runtime < 1):
-          raise AssertionError('Test should have taken 0.05-1 seconds, took %0.1f instead' % runtime)
+        if not (runtime > 0.05 and runtime < 3):
+          raise AssertionError('Test should have taken 0.05-3 seconds, took %0.1f instead' % runtime)

  @asynchronous
  def test_take_ownership_via_pid(tor_cmd):