Update subprocess2.check_output() to behave like subprocess.check_output().

subprocess2.py

Index: subprocess2.py
diff --git a/subprocess2.py b/subprocess2.py
index 5678127aff4e96c1f60e114eec6a2012f9e828b9..895f5a5e19d7e89a09ffd1f2f3e6304d2bac0d03 100644
--- a/subprocess2.py
+++ b/subprocess2.py
@@ -248,7 +248,9 @@ def communicate(args, timeout=None, **kwargs):
 def call(args, **kwargs):
   """Emulates subprocess.call().
 
-  Automatically convert stdout=PIPE or stderr=PIPE to VOID.
+  Automatically convert stdout=PIPE or stderr=PIPE to VOID since in no case they
+  can be returned, no exception is thrown in this code path where stdout is not
+  None.

[Dirk Pranke, 2011/09/09 18:10:38]

Grammar nit: "Automatically converts stdout=PIPE or stderr=PIPE to VOID since
the output isn't returned either way. No exception is thrown when stdout is not
None."

Although I'm not sure why you need to document the second sentence?

[M-A Ruel, 2011/09/09 18:59:21]

Looks like the docstring was unclear since it's not what it meant. Clarified it.

   """
   if kwargs.get('stdout') == PIPE:
     kwargs['stdout'] = VOID
@@ -281,16 +283,12 @@ def capture(args, **kwargs):
   Returns stdout.
 
   - Discards returncode.
-  - Discards stderr. By default sets stderr=STDOUT.
-  - Blocks stdin by default since no output will be visible.
+  - Blocks stdin by default if not specified since no output will be visible.
   """
-  if kwargs.get('stdin') is None:
-    kwargs['stdin'] = VOID
-  if kwargs.get('stdout') is None:
-    kwargs['stdout'] = PIPE
-  if kwargs.get('stderr') is None:
-    kwargs['stderr'] = STDOUT
-  return communicate(args, **kwargs)[0][0]
+  kwargs.setdefault('stdin', VOID)
+
+  # Similar to check_output, deny using stdout arg.

[Dirk Pranke, 2011/09/09 18:10:38]

Grammar nit: "Like check_output(), we ignore any stdout arg that was passed in."

[M-A Ruel, 2011/09/09 18:59:21]

No it's denied. Clarified comment.

+  return communicate(args, stdout=PIPE, **kwargs)[0][0]
 
 
 def check_output(args, **kwargs):
@@ -298,15 +296,10 @@ def check_output(args, **kwargs):
 
   Captures stdout of a process call and returns stdout only.
 
-  - Discards stderr. By default sets stderr=STDOUT.
   - Throws if return code is not 0.
   - Works even prior to python 2.7.
-  - Blocks stdin by default since no output will be visible.
+  - Blocks stdin by default if not specified since no output will be visible.
+  - As per doc, "The stdout argument is not allowed as it is used internally."
   """
-  if kwargs.get('stdin') is None:
-    kwargs['stdin'] = VOID
-  if kwargs.get('stdout') is None:
-    kwargs['stdout'] = PIPE
-  if kwargs.get('stderr') is None:
-    kwargs['stderr'] = STDOUT
-  return check_call_out(args, **kwargs)[0]
+  kwargs.setdefault('stdin', VOID)
+  return check_call_out(args, stdout=PIPE, **kwargs)[0]