Make test_runner and test_windows both use the good Popen

src/allmydata/test/common.py

@@ -9,6 +9,10 @@ __all__ = [
     "flush_logged_errors",
     "skip",
     "skipIf",
+
+    # Selected based on platform and re-exported for convenience.
+    "Popen",
+    "PIPE",
 ]
 
 from past.builtins import chr as byteschr, unicode
@@ -48,6 +52,9 @@ from testtools.twistedsupport import (
     flush_logged_errors,
 )
 
+from twisted.python.runtime import (
+    platform,
+)
 from twisted.application import service
 from twisted.plugin import IPlugin
 from twisted.internet import defer
@@ -101,6 +108,21 @@ from .eliotutil import (
 )
 from .common_util import ShouldFailMixin  # noqa: F401
 
+if platform.isWindows():
+    # Python 2.7 doesn't have good options for launching a process with
+    # non-ASCII in its command line.  So use this alternative that does a
+    # better job.  However, only use it on Windows because it doesn't work
+    # anywhere else.
+    from ._win_subprocess import (
+        PIPE,
+        Popen,
+    )
+else:
+    from subprocess import (
+        PIPE,
+        Popen,
+    )
+
 
 TEST_RSA_KEY_SIZE = 522
 

src/allmydata/test/test_runner.py

@@ -5,10 +5,6 @@ from __future__ import (
 
 import os.path, re, sys
 from os import linesep
-from subprocess import (
-    PIPE,
-    Popen,
-)
 
 from eliot import (
     log_call,
@@ -29,7 +25,14 @@ from twisted.python.runtime import (
 from allmydata.util import fileutil, pollmixin
 from allmydata.test import common_util
 import allmydata
-from .common_util import parse_cli, run_cli
+from .common import (
+    PIPE,
+    Popen,
+)
+from .common_util import (
+    parse_cli,
+    run_cli,
+)
 from .cli_node_api import (
     CLINodeAPI,
     Expect,

src/allmydata/test/test_windows.py

@@ -29,11 +29,6 @@ from json import (
 from textwrap import (
     dedent,
 )
-from subprocess import (
-    PIPE,
-    Popen,
-)
-
 from twisted.python.filepath import (
     FilePath,
 )
@@ -66,6 +61,8 @@ from hypothesis.strategies import (
 )
 
 from .common import (
+    PIPE,
+    Popen,
     SyncTestCase,
 )
 
@@ -132,13 +129,6 @@ class GetArgvTests(SyncTestCase):
         ``get_argv`` returns a list representing the result of tokenizing the
         "command line" argument string provided to Windows processes.
         """
-        # Python 2.7 doesn't have good options for launching a process with
-        # non-ASCII in its command line.  So use this alternative that does a
-        # better job.  Bury the import here because it only works on Windows.
-        from ._win_subprocess import (
-            Popen
-        )
-
         working_path = FilePath(self.mktemp())
         working_path.makedirs()
         save_argv_path = working_path.child("script.py")