[Python-checkins] cpython: Issue #27167: Clarify the subprocess.CalledProcessError error message text

Fri Jun 3 02:14:20 EDT 2016

https://hg.python.org/cpython/rev/f2d13349ea5d
changeset: 101638:f2d13349ea5d
parent: 101636:015b86646d8e
user: Gregory P. Smith <greg at krypto.org> [Google Inc.]
date: Fri Jun 03 06:14:06 2016 +0000
summary:
 Issue #27167: Clarify the subprocess.CalledProcessError error message text
when the child process died due to a signal.
files:
 Lib/subprocess.py | 19 +++++++++++++++----
 Lib/test/test_subprocess.py | 19 +++++++++++++++++++
 Misc/NEWS | 3 +++
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/Lib/subprocess.py b/Lib/subprocess.py
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -372,9 +372,11 @@
 
 
 class CalledProcessError(SubprocessError):
- """This exception is raised when a process run by check_call() or
- check_output() returns a non-zero exit status.
- The exit status will be stored in the returncode attribute;
+ """Raised when a check_call() or check_output() process returns non-zero.
+
+ The exit status will be stored in the returncode attribute, negative
+ if it represents a signal number.
+
 check_output() will also store the output in the output attribute.
 """
 def __init__(self, returncode, cmd, output=None, stderr=None):
@@ -384,7 +386,16 @@
 self.stderr = stderr
 
 def __str__(self):
- return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
+ if self.returncode and self.returncode < 0:
+ try:
+ return "Command '%s' died with %r." % (
+ self.cmd, signal.Signals(-self.returncode))
+ except ValueError:
+ return "Command '%s' died with unknown signal %d." % (
+ self.cmd, -self.returncode)
+ else:
+ return "Command '%s' returned non-zero exit status %d." % (
+ self.cmd, self.returncode)
 
 @property
 def stdout(self):
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1427,6 +1427,25 @@
 p.wait()
 self.assertEqual(-p.returncode, signal.SIGABRT)
 
+ def test_CalledProcessError_str_signal(self):
+ err = subprocess.CalledProcessError(-int(signal.SIGABRT), "fake cmd")
+ error_string = str(err)
+ # We're relying on the repr() of the signal.Signals intenum to provide
+ # the word signal, the signal name and the numeric value.
+ self.assertIn("signal", error_string.lower())
+ self.assertIn("SIGABRT", error_string)
+ self.assertIn(str(signal.SIGABRT), error_string)
+
+ def test_CalledProcessError_str_unknown_signal(self):
+ err = subprocess.CalledProcessError(-9876543, "fake cmd")
+ error_string = str(err)
+ self.assertIn("unknown signal 9876543.", error_string)
+
+ def test_CalledProcessError_str_non_zero(self):
+ err = subprocess.CalledProcessError(2, "fake cmd")
+ error_string = str(err)
+ self.assertIn("non-zero exit status 2.", error_string)
+
 def test_preexec(self):
 # DISCLAIMER: Setting environment variables is *not* a good use
 # of a preexec_fn. This is merely a test.
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -22,6 +22,9 @@
 Library
 -------
 
+- Issue #27167: Clarify the subprocess.CalledProcessError error message text
+ when the child process died due to a signal.
+
 - Issue #25931: Don't define socketserver.Forking* names on platforms such
 as Windows that do not support os.fork().
 
-- 
Repository URL: https://hg.python.org/cpython
