[subprocess2] Replace VOID with DEVNULL

subprocess.DEVNULL was introduced in Python3 to serve same purpose
as subprocess2.VOID, so rename VOID to DEVNULL in subprocess2.

Change-Id: I6dade3306ffc3bc2441ac6083f362b099c2427e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2587758
Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

cit.py

@@ -40,7 +40,7 @@ def need_to_update(branch):
   try:
     cmd = [sys.executable, GCLIENT, 'revinfo']
     subprocess.check_call(
-        cmd, cwd=os.path.join(TARGET_DIR), stdout=subprocess.VOID)
+        cmd, cwd=os.path.join(TARGET_DIR), stdout=subprocess.DEVNULL)
   except subprocess.CalledProcessError:
     return True  # Gclient failed, definitely need to update.
   except OSError:
@@ -53,7 +53,7 @@ def need_to_update(branch):
 
   subprocess.check_call(
       ['git', 'fetch', 'origin'], cwd=INFRA_DIR,
-      stdout=subprocess.VOID, stderr=subprocess.STDOUT)
+      stdout=subprocess.DEVNULL, stderr=subprocess.STDOUT)
   origin_rev = get_git_rev(INFRA_DIR, 'origin/%s' % (branch,))
   return origin_rev != local_rev
 
@@ -70,11 +70,11 @@ def ensure_infra(branch):
     subprocess.check_call(
         [sys.executable, os.path.join(SCRIPT_DIR, 'fetch.py'), 'infra'],
         cwd=TARGET_DIR,
-        stdout=subprocess.VOID)
+        stdout=subprocess.DEVNULL)
   subprocess.check_call(
       [sys.executable, GCLIENT, 'sync', '--revision', 'origin/%s' % (branch,)],
       cwd=TARGET_DIR,
-      stdout=subprocess.VOID)
+      stdout=subprocess.DEVNULL)
   sys.stderr.write(' done.\n')
   sys.stderr.flush()
 

git_cl.py

@@ -195,7 +195,7 @@ def RunGit(args, **kwargs):
 def RunGitWithCode(args, suppress_stderr=False):
   """Returns return code and stdout."""
   if suppress_stderr:
-    stderr = subprocess2.VOID
+    stderr = subprocess2.DEVNULL
   else:
     stderr = sys.stderr
   try:

git_common.py

@@ -743,7 +743,7 @@ def run_stream(*cmd, **kwargs):
   stderr is dropped to avoid races if the process outputs to both stdout and
   stderr.
   """
-  kwargs.setdefault('stderr', subprocess2.VOID)
+  kwargs.setdefault('stderr', subprocess2.DEVNULL)
   kwargs.setdefault('stdout', subprocess2.PIPE)
   kwargs.setdefault('shell', False)
   cmd = (GIT_EXE, '-c', 'color.ui=never') + cmd
@@ -760,7 +760,7 @@ def run_stream_with_retcode(*cmd, **kwargs):
 
   Raises subprocess2.CalledProcessError on nonzero return code.
   """
-  kwargs.setdefault('stderr', subprocess2.VOID)
+  kwargs.setdefault('stderr', subprocess2.DEVNULL)
   kwargs.setdefault('stdout', subprocess2.PIPE)
   kwargs.setdefault('shell', False)
   cmd = (GIT_EXE, '-c', 'color.ui=never') + cmd

roll_dep.py

@@ -63,10 +63,10 @@ def check_call(*args, **kwargs):
 
 def return_code(*args, **kwargs):
   """subprocess2.call() passing shell=True on Windows for git and
-  subprocess2.VOID for stdout and stderr."""
+  subprocess2.DEVNULL for stdout and stderr."""
   kwargs.setdefault('shell', NEED_SHELL)
-  kwargs.setdefault('stdout', subprocess2.VOID)
-  kwargs.setdefault('stderr', subprocess2.VOID)
+  kwargs.setdefault('stdout', subprocess2.DEVNULL)
+  kwargs.setdefault('stderr', subprocess2.DEVNULL)
   return subprocess2.call(*args, **kwargs)
 
 

scm.py

@@ -75,8 +75,8 @@ def determine_scm(root):
     try:
       subprocess2.check_call(
           ['git', 'rev-parse', '--show-cdup'],
-          stdout=subprocess2.VOID,
-          stderr=subprocess2.VOID,
+          stdout=subprocess2.DEVNULL,
+          stderr=subprocess2.DEVNULL,
           cwd=root)
       return 'git'
     except (OSError, subprocess2.CalledProcessError):

subprocess2.py

@@ -21,18 +21,18 @@ import threading
 if sys.version_info.major == 2:
   import Queue
   codecs.lookup('string-escape')
+  # Sends stdout or stderr to os.devnull.
+  DEVNULL = open(os.devnull, 'r+')
 else:
   import queue as Queue
   # pylint: disable=redefined-builtin
   basestring = (str, bytes)
+  DEVNULL = subprocess.DEVNULL
 
 
 # Constants forwarded from subprocess.
 PIPE = subprocess.PIPE
 STDOUT = subprocess.STDOUT
-# Sends stdout or stderr to os.devnull.
-VOID = open(os.devnull, 'w')
-VOID_INPUT = open(os.devnull, 'r')
 
 
 class CalledProcessError(subprocess.CalledProcessError):
@@ -107,7 +107,7 @@ class Popen(subprocess.Popen):
     in English.
   - Sets shell=True on windows by default. You can override this by forcing
     shell parameter to a value.
-  - Adds support for VOID to not buffer when not needed.
+  - Adds support for DEVNULL to not buffer when not needed.
   - Adds self.start property.
 
   Note: Popen() can throw OSError when cwd or args[0] doesn't exist. Translate
@@ -197,16 +197,16 @@ def communicate(args, **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 DEVNULL.
   In no case they can be returned since no code path raises
   subprocess2.CalledProcessError.
 
   Returns exit code.
   """
   if kwargs.get('stdout') == PIPE:
-    kwargs['stdout'] = VOID
+    kwargs['stdout'] = DEVNULL
   if kwargs.get('stderr') == PIPE:
-    kwargs['stderr'] = VOID
+    kwargs['stderr'] = DEVNULL
   return communicate(args, **kwargs)[1]
 
 
@@ -236,7 +236,7 @@ def capture(args, **kwargs):
   - Discards returncode.
   - Blocks stdin by default if not specified since no output will be visible.
   """
-  kwargs.setdefault('stdin', VOID_INPUT)
+  kwargs.setdefault('stdin', DEVNULL)
 
   # Like check_output, deny the caller from using stdout arg.
   return communicate(args, stdout=PIPE, **kwargs)[0][0]
@@ -252,7 +252,7 @@ def check_output(args, **kwargs):
   - 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."
   """
-  kwargs.setdefault('stdin', VOID_INPUT)
+  kwargs.setdefault('stdin', DEVNULL)
   if 'stdout' in kwargs:
     raise ValueError('stdout argument not allowed, it would be overridden.')
   return check_call_out(args, stdout=PIPE, **kwargs)[0]

tests/subprocess2_test.py

@@ -42,7 +42,7 @@ class DefaultsTest(unittest.TestCase):
     self.assertEqual(
         'stdout', subprocess2.capture(['foo'], a=True))
     mockCommunicate.assert_called_with(
-        ['foo'], a=True, stdin=subprocess2.VOID_INPUT, stdout=subprocess2.PIPE)
+        ['foo'], a=True, stdin=subprocess2.DEVNULL, stdout=subprocess2.PIPE)
 
   @mock.patch('subprocess2.Popen')
   def test_communicate_defaults(self, mockPopen):
@@ -80,7 +80,7 @@ class DefaultsTest(unittest.TestCase):
     mockCommunicate.return_value = (('stdout', 'stderr'), 0)
     self.assertEqual('stdout', subprocess2.check_output(['foo'], a=True))
     mockCommunicate.assert_called_with(
-        ['foo'], a=True, stdin=subprocess2.VOID_INPUT, stdout=subprocess2.PIPE)
+        ['foo'], a=True, stdin=subprocess2.DEVNULL, stdout=subprocess2.PIPE)
 
   @mock.patch('subprocess.Popen.__init__')
   def test_env_type(self, mockPopen):
@@ -241,15 +241,15 @@ class SmokeTests(unittest.TestCase):
   def test_stdin_void(self):
     res = subprocess2.communicate(
         TEST_COMMAND + ['--read'],
-        stdin=subprocess2.VOID_INPUT)
+        stdin=subprocess2.DEVNULL)
     self._check_res(res, None, None, 0)
 
   @_run_test(with_subprocess=False)
   def test_stdin_void_stdout(self, c, cmd, un, subp):
-    # Make sure a mix ofsubprocess2.VOID andsubprocess2.PIPE works.
+    # Make sure a mix ofsubprocess2.DEVNULL andsubprocess2.PIPE works.
     res = subprocess2.communicate(
         cmd + ['--stdout', '--read'],
-        stdin=subprocess2.VOID_INPUT,
+        stdin=subprocess2.DEVNULL,
         stdout=subprocess2.PIPE,
         universal_newlines=un,
         shell=False)
@@ -259,7 +259,7 @@ class SmokeTests(unittest.TestCase):
   def test_stdout_void(self, c, cmd, un, subp):
     res = subprocess2.communicate(
         cmd + ['--stdout', '--stderr'],
-        stdout=subprocess2.VOID,
+        stdout=subprocess2.DEVNULL,
         stderr=subprocess2.PIPE,
         universal_newlines=un)
     self._check_res(res, None, c('a\nbb\nccc\n'), 0)
@@ -269,7 +269,7 @@ class SmokeTests(unittest.TestCase):
     res = subprocess2.communicate(
         cmd + ['--stdout', '--stderr'],
         stdout=subprocess2.PIPE,
-        stderr=subprocess2.VOID,
+        stderr=subprocess2.DEVNULL,
         universal_newlines=un)
     self._check_res(res, c('A\nBB\nCCC\n'), None, 0)
 
@@ -277,7 +277,7 @@ class SmokeTests(unittest.TestCase):
   def test_stdout_void_stderr_redirect(self, c, cmd, un, subp):
     res = subprocess2.communicate(
         cmd + ['--stdout', '--stderr'],
-        stdout=subprocess2.VOID,
+        stdout=subprocess2.DEVNULL,
         stderr=subprocess2.STDOUT,
         universal_newlines=un)
     self._check_res(res, None, None, 0)