Add hacking check to ensure _ is imported

Added hacking check to ensure that _ is imported and allows multiple
imports from i18n module per line.

Change-Id: Ieffabd6f2fe866000c5dc1d9ce83acd2f9ab0450

HACKING.rst

@@ -2,3 +2,8 @@ masakari-monitors Style Commandments
 ===============================================
 
 Read the OpenStack Style Commandments http://docs.openstack.org/developer/hacking/
+
+masakari-monitors Specific Commandments
+------------------------------
+
+- [M301] Ensure that the _() function is explicitly imported to ensure proper translations.

masakarimonitors/hacking/checks.py

@@ -0,0 +1,70 @@
+# Copyright (c) 2017, NTT Data
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import re
+
+
+"""
+Guidelines for writing new hacking checks
+
+ - Use only for masakarimonitors specific tests. OpenStack general tests
+   should be submitted to the common 'hacking' module.
+ - Pick numbers in the range M3xx. Find the current test with
+   the highest allocated number and then pick the next value.
+ - Keep the test method code in the source file ordered based
+   on the M3xx value.
+ - List the new rule in the top level HACKING.rst file
+ - Add test cases for each new rule to masakarimonitors/tests/unit/
+   test_hacking.py
+
+"""
+
+UNDERSCORE_IMPORT_FILES = []
+
+translated_log = re.compile(
+    r"(.)*LOG\.(audit|error|info|critical|exception)"
+    "\(\s*_\(\s*('|\")")
+string_translation = re.compile(r"[^_]*_\(\s*('|\")")
+underscore_import_check = re.compile(r"(.)*import _(.)*")
+underscore_import_check_multi = re.compile(r"(.)*i18n\s+import(.)* _, (.)*")
+# We need this for cases where they have created their own _ function.
+custom_underscore_check = re.compile(r"(.)*_\s*=\s*(.)*")
+
+
+def check_explicit_underscore_import(logical_line, filename):
+    """Check for explicit import of the _ function
+
+    We need to ensure that any files that are using the _() function
+    to translate logs are explicitly importing the _ function.  We
+    can't trust unit test to catch whether the import has been
+    added so we need to check for it here.
+    """
+
+    # Build a list of the files that have _ imported.  No further
+    # checking needed once it is found.
+    for file in UNDERSCORE_IMPORT_FILES:
+        if file in filename:
+            return
+    if (underscore_import_check.match(logical_line) or
+            underscore_import_check_multi.match(logical_line) or
+            custom_underscore_check.match(logical_line)):
+        UNDERSCORE_IMPORT_FILES.append(filename)
+    elif(translated_log.match(logical_line) or
+         string_translation.match(logical_line)):
+        yield(0, "M301: Found use of _() without explicit import of _ !")
+
+
+def factory(register):
+    register(check_explicit_underscore_import)

masakarimonitors/tests/unit/test_hacking.py

@@ -0,0 +1,79 @@
+#    Copyright 2017 NTT Data.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import testtools
+
+from masakarimonitors.hacking import checks
+
+
+class HackingTestCase(testtools.TestCase):
+    """This class tests the hacking checks in masakarimonitors.hacking.checks by
+    passing strings to the check methods like the pep8/flake8 parser would.
+    The parser loops over each line in the file and then passes the
+    parameters to the check method. The parameter names in the check method
+    dictate what type of object is passed to the check method.
+
+    The parameter types are::
+
+        logical_line: A processed line with the following modifications:
+            - Multi-line statements converted to a single line.
+            - Stripped left and right.
+            - Contents of strings replaced with "xxx" of same length.
+            - Comments removed.
+        physical_line: Raw line of text from the input file.
+        lines: a list of the raw lines from the input file
+        tokens: the tokens that contribute to this logical line
+        line_number: line number in the input file
+        total_lines: number of lines in the input file
+        blank_lines: blank lines before this one
+        indent_char: indentation character in this file (" " or "\t")
+        indent_level: indentation (with tabs expanded to multiples of 8)
+        previous_indent_level: indentation on previous line
+        previous_logical: previous logical line
+        filename: Path of the file being run through pep8
+
+    When running a test on a check method the return will be False/None if
+    there is no violation in the sample input. If there is an error a tuple is
+    returned with a position in the line, and a message. So to check the result
+    just assertTrue if the check is expected to fail and assertFalse if it
+    should pass.
+    """
+    def test_check_explicit_underscore_import(self):
+        self.assertEqual(len(list(checks.check_explicit_underscore_import(
+            "LOG.info(_('My info message'))",
+            "masakarimonitors/tests/other_files.py"))), 1)
+        self.assertEqual(len(list(checks.check_explicit_underscore_import(
+            "msg = _('My message')",
+            "masakarimonitors/tests/other_files.py"))), 1)
+        self.assertEqual(len(list(checks.check_explicit_underscore_import(
+            "from masakarimonitors.i18n import _",
+            "masakarimonitors/tests/other_files.py"))), 0)
+        self.assertEqual(len(list(checks.check_explicit_underscore_import(
+            "LOG.info(_('My info message'))",
+            "masakarimonitors/tests/other_files.py"))), 0)
+        self.assertEqual(len(list(checks.check_explicit_underscore_import(
+            "msg = _('My message')",
+            "masakarimonitors/tests/other_files.py"))), 0)
+        self.assertEqual(len(list(checks.check_explicit_underscore_import(
+            "from masakarimonitors.i18n import _, _LW",
+            "masakarimonitors/tests/other_files2.py"))), 0)
+        self.assertEqual(len(list(checks.check_explicit_underscore_import(
+            "msg = _('My message')",
+            "masakarimonitors/tests/other_files2.py"))), 0)
+        self.assertEqual(len(list(checks.check_explicit_underscore_import(
+            "_ = translations.ugettext",
+            "masakarimonitors/tests/other_files3.py"))), 0)
+        self.assertEqual(len(list(checks.check_explicit_underscore_import(
+            "msg = _('My message')",
+            "masakarimonitors/tests/other_files3.py"))), 0)

tox.ini

@@ -35,9 +35,17 @@ commands =
 commands = oslo_debug_helper {posargs}
 
 [flake8]
-# E123, E125 skipped as they are invalid PEP-8.
+# E123 - closing bracket does not match indentation of opening bracket's line
+# E125 - continuation line with same indent as next logical line
+# E128 - continuation line under-indented for visual indent
+# E265 - block comment should start with '# '
+# H405 - multi line docstring summary not separated with an empty line
 
 show-source = True
-ignore = E123,E125
+ignore = E123,E125,E128,E265,H405
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build
+
+[hacking]
+import_exceptions = masakarimonitors.i18n
+