Actually test ProxyCommand as currently implemented

Including shuffling around the imports therein so they can actually be
mocked, without losing the property of "can be imported under GAE".

1 files changed, 15 insertions, 8 deletions

diff --git a/paramiko/proxy.py b/paramiko/proxy.py
index 444c47b6..61591b81 100644
--- a/paramiko/proxy.py
+++ b/paramiko/proxy.py
@@ -18,12 +18,20 @@
 
 
 import os
-from shlex import split as shlsplit
+import shlex
 import signal
 from select import select
 import socket
 import time
 
+# Try-and-ignore import so platforms w/o subprocess (eg Google App Engine) can
+# still import paramiko.
+subprocess, subprocess_import_error = None, None
+try:
+    import subprocess
+except ImportError as e:
+    pass
+
 from paramiko.ssh_exception import ProxyCommandFailure
 from paramiko.util import ClosingContextManager
 
@@ -48,13 +56,12 @@ class ProxyCommand(ClosingContextManager):
         :param str command_line:
             the command that should be executed and used as the proxy.
         """
-        # NOTE: subprocess import done lazily so platforms without it (e.g.
-        # GAE) can still import us during overall Paramiko load.
-        from subprocess import Popen, PIPE
-
-        self.cmd = shlsplit(command_line)
-        self.process = Popen(
-            self.cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE, bufsize=0
+        if subprocess is None:
+            raise subprocess_import_error
+        self.cmd = shlex.split(command_line)
+        self.process = subprocess.Popen(
+            self.cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE, bufsize=0
         )
         self.timeout = None