Move check_output() to shared function

Remove two duplicated check_output() functions.

This also fixes a Python 2.6 error that when the subprocess exited with
non-zero check_output() was calling CalledProcessError with an argument
that doesn't exist in 2.6.

ckan/lib/util.py

@@ -0,0 +1,45 @@
+'''Shared utility functions for any Python code to use.
+
+Unlike :py:func:`ckan.lib.helpers`, the functions in this module are not
+available to templates.
+
+'''
+import subprocess
+
+
+# We implement our own check_output() function because
+# subprocess.check_output() isn't in Python 2.6.
+# This code is copy-pasted from Python 2.7 and adapted to make it work with
+# Python 2.6.
+# http://hg.python.org/cpython/file/d37f963394aa/Lib/subprocess.py#l544
+def check_output(*popenargs, **kwargs):
+    r"""Run command with arguments and return its output as a byte string.
+
+    If the exit code was non-zero it raises a CalledProcessError.  The
+    CalledProcessError object will have the return code in the returncode
+    attribute and output in the output attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    >>> check_output(["ls", "-l", "/dev/null"])
+    'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'
+
+    The stdout argument is not allowed as it is used internally.
+    To capture standard error in the result, use stderr=STDOUT.
+
+    >>> check_output(["/bin/sh", "-c",
+    ...               "ls -l non_existent_file ; exit 0"],
+    ...              stderr=STDOUT)
+    'ls: non_existent_file: No such file or directory\n'
+    """
+    if 'stdout' in kwargs:
+        raise ValueError('stdout argument not allowed, it will be overridden.')
+    process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
+    output, unused_err = process.communicate()
+    retcode = process.poll()
+    if retcode:
+        cmd = kwargs.get("args")
+        if cmd is None:
+            cmd = popenargs[0]
+        raise subprocess.CalledProcessError(retcode, cmd)
+    return output

ckan/new_tests/test_coding_standards.py

@@ -8,42 +8,7 @@
 '''
 import subprocess
 
-
-# We implement our own check_output() function because
-# subprocess.check_output() isn't in Python 2.6.
-# This code is copy-pasted from Python 2.7:
-# http://hg.python.org/cpython/file/d37f963394aa/Lib/subprocess.py#l544
-def check_output(*popenargs, **kwargs):
-    r"""Run command with arguments and return its output as a byte string.
-
-    If the exit code was non-zero it raises a CalledProcessError.  The
-    CalledProcessError object will have the return code in the returncode
-    attribute and output in the output attribute.
-
-    The arguments are the same as for the Popen constructor.  Example:
-
-    >>> check_output(["ls", "-l", "/dev/null"])
-    'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'
-
-    The stdout argument is not allowed as it is used internally.
-    To capture standard error in the result, use stderr=STDOUT.
-
-    >>> check_output(["/bin/sh", "-c",
-    ...               "ls -l non_existent_file ; exit 0"],
-    ...              stderr=STDOUT)
-    'ls: non_existent_file: No such file or directory\n'
-    """
-    if 'stdout' in kwargs:
-        raise ValueError('stdout argument not allowed, it will be overridden.')
-    process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
-    output, unused_err = process.communicate()
-    retcode = process.poll()
-    if retcode:
-        cmd = kwargs.get("args")
-        if cmd is None:
-            cmd = popenargs[0]
-        raise subprocess.CalledProcessError(retcode, cmd, output=output)
-    return output
+import ckan.lib.util as util
 
 
 def test_building_the_docs():
@@ -52,17 +17,17 @@ def test_building_the_docs():
     This test unfortunately does take quite a long time to run - rebuilding the
     docs from scratch just takes a long time.
 
-    This test will also fail is build_sphinx exits with non-zero status
-    (because subprocess.check_output() will raise an exception).
+    This test will also fail is build_sphinx exits with non-zero status.
 
     '''
     try:
-        output = check_output(
+        output = util.check_output(
             ['python', 'setup.py', 'build_sphinx', '--all-files', '--fresh-env'],
             stderr=subprocess.STDOUT)
     except subprocess.CalledProcessError as err:
-        assert False, "Building the docs failed: {err}".format(
-            err=err.message + ' ' + err.output)
+        assert False, (
+            "Building the docs failed with return code: {code}".format(
+                code=err.returncode))
     output_lines = output.split('\n')
 
     errors = [line for line in output_lines if 'ERROR' in line]

doc/conf.py

@@ -18,6 +18,8 @@
 import os
 import subprocess
 
+import ckan.lib.util as util
+
 # If your extensions (or modules documented by autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
@@ -115,43 +117,6 @@
 release = ckan.__version__
 
 
-# We implement our own check_output() function because
-# subprocess.check_output() isn't in Python 2.6.
-# This code is copy-pasted from Python 2.7:
-# http://hg.python.org/cpython/file/d37f963394aa/Lib/subprocess.py#l544
-def check_output(*popenargs, **kwargs):
-    r"""Run command with arguments and return its output as a byte string.
-
-    If the exit code was non-zero it raises a CalledProcessError.  The
-    CalledProcessError object will have the return code in the returncode
-    attribute and output in the output attribute.
-
-    The arguments are the same as for the Popen constructor.  Example:
-
-    >>> check_output(["ls", "-l", "/dev/null"])
-    'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'
-
-    The stdout argument is not allowed as it is used internally.
-    To capture standard error in the result, use stderr=STDOUT.
-
-    >>> check_output(["/bin/sh", "-c",
-    ...               "ls -l non_existent_file ; exit 0"],
-    ...              stderr=STDOUT)
-    'ls: non_existent_file: No such file or directory\n'
-    """
-    if 'stdout' in kwargs:
-        raise ValueError('stdout argument not allowed, it will be overridden.')
-    process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
-    output, unused_err = process.communicate()
-    retcode = process.poll()
-    if retcode:
-        cmd = kwargs.get("args")
-        if cmd is None:
-            cmd = popenargs[0]
-        raise subprocess.CalledProcessError(retcode, cmd, output=output)
-    return output
-
-
 def latest_release_tag():
     '''Return the name of the git tag for the latest stable release.
 
@@ -160,7 +125,7 @@ def latest_release_tag():
     This requires git to be installed.
 
     '''
-    git_tags = check_output(
+    git_tags = util.check_output(
         ['git', 'tag', '-l'], stderr=subprocess.STDOUT).split()
 
     # FIXME: We could do more careful pattern matching against ckan-X.Y.Z here.