Localized exception message hacking check

As per [1], this patch adds a new hacking check that verifies
raised exceptions don't use unlocalized string messages. This
patch also adds unit tests for the new check and enables
checks for neutron-lib itself (as per tox.ini).

Note: Perhaps this check better belongs in openstack-dev/hacking
but it seems we already have a number of more generic checks
in neutron. We can discuss that here need be.

NB: Without [1] this new hacking check fails when running pep8 on
neutron-lib.

[1] https://review.openstack.org/#/c/324374/

Change-Id: Ia13f190ec6843ab360d115871d345c4ddc302cc5

HACKING.rst

@@ -19,3 +19,4 @@ Neutron Specific Commandments
 - [N531] Validate that LOG messages, except debug ones, have translations
 - [N532] Validate that LOG.warning is used instead of LOG.warn. The latter is deprecated.
 - [N533] Validate that debug level logs are not translated
+- [N534] Exception messages should be translated

neutron_lib/hacking/checks.py

@@ -160,3 +160,4 @@ def factory(register):
     register(translation_checks.validate_log_translations)
     register(translation_checks.no_translate_debug_logs)
     register(translation_checks.check_log_warn_deprecated)
+    register(translation_checks.check_raised_localized_exceptions)

neutron_lib/hacking/translation_checks.py

@@ -75,3 +75,18 @@ def no_translate_debug_logs(logical_line, filename):
     for hint in _all_hints:
         if logical_line.startswith("LOG.debug(%s(" % hint):
             yield(0, "N533 Don't translate debug level logs")
+
+
+def check_raised_localized_exceptions(logical_line, filename):
+    # NOTE(boden): tox.ini doesn't permit per check exclusion
+    if "/tests/" in filename:
+        return
+
+    logical_line = logical_line.strip()
+    raised_search = re.compile(
+        r"raise (?:\w*)\((.*)\)").match(logical_line)
+    if raised_search:
+        exception_msg = raised_search.groups()[0]
+        if exception_msg.startswith("\"") or exception_msg.startswith("\'"):
+            msg = "N534: Untranslated exception message."
+            yield (logical_line.index(exception_msg), msg)

neutron_lib/tests/unit/hacking/test_checks.py

@@ -19,12 +19,12 @@ from neutron_lib.tests import _base as base
 
 class HackingTestCase(base.BaseTestCase):
 
-    def assertLinePasses(self, func, line):
+    def assertLinePasses(self, func, *args):
         with testtools.ExpectedException(StopIteration):
-            next(func(line))
+            next(func(*args))
 
-    def assertLineFails(self, func, line):
-        self.assertIsInstance(next(func(line)), tuple)
+    def assertLineFails(self, func, *args):
+        self.assertIsInstance(next(func(*args)), tuple)
 
     def test_use_jsonutils(self):
         def __get_msg(fun):
@@ -149,3 +149,19 @@ class HackingTestCase(base.BaseTestCase):
         bad = "LOG.warn(_LW('i am deprecated!'))"
         self.assertEqual(
             1, len(list(tc.check_log_warn_deprecated(bad, 'f'))))
+
+    def test_check_localized_exception_messages(self):
+        f = tc.check_raised_localized_exceptions
+        self.assertLineFails(f, "     raise KeyError('Error text')", '')
+        self.assertLineFails(f, ' raise KeyError("Error text")', '')
+        self.assertLinePasses(f, ' raise KeyError(_("Error text"))', '')
+        self.assertLinePasses(f, ' raise KeyError(_ERR("Error text"))', '')
+        self.assertLinePasses(f, " raise KeyError(translated_msg)", '')
+        self.assertLinePasses(f, '# raise KeyError("Not translated")', '')
+        self.assertLinePasses(f, 'print("raise KeyError("Not '
+                                 'translated")")', '')
+
+    def test_check_localized_exception_message_skip_tests(self):
+        f = tc.check_raised_localized_exceptions
+        self.assertLinePasses(f, "raise KeyError('Error text')",
+                              'neutron_lib/tests/unit/mytest.py')