Work around subprocess.CalledProcessError on Google App Engine

daradib · daradib · commit 15d09a59004e · 2014-03-03T11:08:53.000-08:00
Set subprocess.CalledProcessError to None on restrictive environments like Google App Engine because the exception cannot be raised and there is no need to catch it. Fixes #1825 which broke after #1857.
diff --git a/lib/matplotlib/compat/subprocess.py b/lib/matplotlib/compat/subprocess.py
@@ -18,21 +18,25 @@
 
 import subprocess
 
-__all__ = ['Popen', 'PIPE', 'STDOUT', 'check_output']
+__all__ = ['Popen', 'PIPE', 'STDOUT', 'check_output', 'CalledProcessError']
 
 
 if hasattr(subprocess, 'Popen'):
     Popen = subprocess.Popen
     # Assume that it also has the other constants.
     PIPE = subprocess.PIPE
     STDOUT = subprocess.STDOUT
+    CalledProcessError = subprocess.CalledProcessError
 else:
     # In restricted environments (such as Google App Engine), these are
     # non-existent. Replace them with dummy versions that always raise OSError.
     def Popen(*args, **kwargs):
         raise OSError("subprocess.Popen is not supported")
     PIPE = -1
     STDOUT = -2
+    # There is no need to catch CalledProcessError. These stubs cannot raise
+    # it. None in an except clause will simply not match any exceptions.
+    CalledProcessError = None
 
 
 def _check_output(*popenargs, **kwargs):
@@ -75,5 +79,3 @@ def _check_output(*popenargs, **kwargs):
     check_output = subprocess.check_output
 else:
     check_output = _check_output
-
-CalledProcessError = subprocess.CalledProcessError
