Make the --py3k flag commutative with the -E flag.

Also, this patch fixes the leaks of error messages from the Python 3
checker when the errors mode was activated. Closes issue #437.

5 files changed, 87 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 821e826..bdf395a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -48,6 +48,10 @@ RELEASE DATE -- VERSION
       emitted when the `cmp` argument for the `list.sort` or `sorted builtin`
       is encountered.
 
+    * Make the --py3k flag commutative with the -E flag. Also, this patch
+      fixes the leaks of error messages from the Python 3 checker when
+      the errors mode was activated. Closes issue #437.
+
 
 2015-01-16 -- 1.4.1
 
diff --git a/pylint/lint.py b/pylint/lint.py
index 7274c78..5ac51c2 100644
--- a/pylint/lint.py
+++ b/pylint/lint.py
@@ -455,6 +455,7 @@ class PyLinter(configuration.OptionsManagerMixIn,
         self.register_checker(self)
         self._dynamic_plugins = set()
         self._python3_porting_mode = False
+        self._error_mode = False
         self.load_provider_defaults()
         if reporter:
             self.set_reporter(reporter)
@@ -583,8 +584,16 @@ class PyLinter(configuration.OptionsManagerMixIn,
 
     def error_mode(self):
         """error mode: enable only errors; no reports, no persistent"""
+        self._error_mode = True
         self.disable_noerror_messages()
         self.disable('miscellaneous')
+        if self._python3_porting_mode:
+            self.disable('all')
+            for msg_id in self._checker_messages('python3'):
+                if msg_id.startswith('E'):
+                    self.enable(msg_id)
+        else:
+            self.disable('python3')
         self.set_option('reports', False)
         self.set_option('persistent', False)
 
@@ -592,6 +601,15 @@ class PyLinter(configuration.OptionsManagerMixIn,
         """Disable all other checkers and enable Python 3 warnings."""
         self.disable('all')
         self.enable('python3')
+        if self._error_mode:
+            # The error mode was activated, using the -E flag.
+            # So we'll need to enable only the errors from the
+            # Python 3 porting checker.
+            for msg_id in self._checker_messages('python3'):
+                if msg_id.startswith('E'):
+                    self.enable(msg_id)
+                else:
+                    self.disable(msg_id)
         self._python3_porting_mode = True
 
     # block level option handling #############################################
diff --git a/pylint/test/regrtest_data/py3k_error_flag.py b/pylint/test/regrtest_data/py3k_error_flag.py
new file mode 100644
index 0000000..c12d250
--- /dev/null
+++ b/pylint/test/regrtest_data/py3k_error_flag.py
@@ -0,0 +1,11 @@
+"""Contains both normal error messages and Python3 porting error messages."""

+# pylint: disable=bad-builtin, too-few-public-methods

+

+raise Exception, 1  # Error emitted here with the Python 3 checker.

+

+

+class Test(object):

+    """dummy"""

+

+    def __init__(self):

+        return 42

diff --git a/pylint/test/test_self.py b/pylint/test/test_self.py
index 1734889..9c296b8 100644
--- a/pylint/test/test_self.py
+++ b/pylint/test/test_self.py
@@ -11,10 +11,12 @@
 # this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 
+import contextlib
 import sys
 import os
 from os.path import join, dirname, abspath
 import tempfile
+import textwrap
 import unittest
 
 import six
@@ -28,6 +30,17 @@ from pylint.reporters.json import JSONReporter
 HERE = abspath(dirname(__file__))
 
 
+
+@contextlib.contextmanager
+def _patch_streams(out):
+    sys.stderr = sys.stdout = out
+    try:
+        yield
+    finally:
+        sys.stderr = sys.__stderr__
+        sys.stdout = sys.__stdout__
+
+
 class MultiReporter(BaseReporter):
     def __init__(self, reporters):
         self._reporters = reporters
@@ -85,6 +98,15 @@ class RunTC(unittest.TestCase):
             sys.stderr = sys.__stderr__
             sys.stdout = sys.__stdout__
 
+    def _test_output(self, args, expected_output):
+        out = six.StringIO()
+        with _patch_streams(out):
+            with self.assertRaises(SystemExit):
+                Run(args)
+
+            actual_output = out.getvalue()
+            self.assertEqual(expected_output.strip(), actual_output.strip())
+
     def test_pkginfo(self):
         """Make pylint check itself."""
         self._runtest(['pylint.__pkginfo__'], reporter=TextReporter(six.StringIO()),
@@ -151,7 +173,33 @@ class RunTC(unittest.TestCase):
         rc_code = 2 if six.PY2 else 0
         self._runtest([join(HERE, 'functional', 'unpacked_exceptions.py'),
                        '--py3k', '-j 2'],
-                      code=rc_code) 
+                      code=rc_code)
+
+    @unittest.skipIf(sys.version_info[0] > 2, "Requires the --py3k flag.")
+    def test_py3k_commutative_with_errors_only(self):
+
+        # Test what gets emitted with -E only
+        module = join(HERE, 'regrtest_data', 'py3k_error_flag.py')
+        expected = textwrap.dedent("""
+        No config file found, using default configuration
+        ************* Module py3k_error_flag
+        Explicit return in __init__
+        """)
+        self._test_output([module, "-E", "--msg-template='{msg}'"],
+                          expected_output=expected)
+
+        # Test what gets emitted with -E --py3k
+        expected = textwrap.dedent("""
+        No config file found, using default configuration
+        ************* Module py3k_error_flag
+        Use raise ErrorClass(args) instead of raise ErrorClass, args.
+        """)
+        self._test_output([module, "-E", "--py3k", "--msg-template='{msg}'"],
+                          expected_output=expected)
+
+        # Test what gets emitted with --py3k -E
+        self._test_output([module, "--py3k", "-E", "--msg-template='{msg}'"],
+                          expected_output=expected)
 
 
 if __name__ == '__main__':
diff --git a/pylint/utils.py b/pylint/utils.py
index 6685c4a..6c5b975 100644
--- a/pylint/utils.py
+++ b/pylint/utils.py
@@ -225,6 +225,11 @@ class MessagesHandlerMixIn(object):
         self._msgs_state = {}
         self.msg_status = 0
 
+    def _checker_messages(self, checker):
+        for checker in self._checkers[checker.lower()]:
+            for msgid in checker.msgs:
+                yield msgid
+
     def disable(self, msgid, scope='package', line=None, ignore_unknown=False):
         """don't output message of the given id"""
         assert scope in ('package', 'module')