Allow our local plugin parsing to accept commas

By slightly modifying our utility function to parse comma separated
lists we can parse local plugins similar to other configuration options.

src/flake8/options/config.py

@@ -5,6 +5,8 @@ import logging
 import os.path
 import sys
 
+from flake8 import utils
+
 LOG = logging.getLogger(__name__)
 
 __all__ = ('ConfigFileFinder', 'MergedConfigParser')
@@ -320,11 +322,12 @@ def get_local_plugins(config_finder, cli_config=None, isolated=False):
     section = '%s:local-plugins' % config_finder.program_name
     for plugin_type in ['extension', 'report']:
         if config.has_option(section, plugin_type):
-            getattr(local_plugins, plugin_type).extend(
-                c.strip() for c in config.get(
-                    section, plugin_type
-                ).strip().splitlines()
-            )
+            local_plugins_string = config.get(section, plugin_type).strip()
+            plugin_type_list = getattr(local_plugins, plugin_type)
+            plugin_type_list.extend(utils.parse_comma_separated_list(
+                local_plugins_string,
+                regexp=utils.LOCAL_PLUGIN_LIST_RE,
+            ))
     return local_plugins
 
 

src/flake8/utils.py

@@ -11,14 +11,20 @@ import tokenize
 
 DIFF_HUNK_REGEXP = re.compile(r'^@@ -\d+(?:,\d+)? \+(\d+)(?:,(\d+))? @@.*$')
 COMMA_SEPARATED_LIST_RE = re.compile(r'[,\s]')
+LOCAL_PLUGIN_LIST_RE = re.compile(r'[,\t\n\r\f\v]')
 
 
-def parse_comma_separated_list(value):
+def parse_comma_separated_list(value, regexp=COMMA_SEPARATED_LIST_RE):
     # type: (Union[Sequence[str], str]) -> List[str]
     """Parse a comma-separated list.
 
     :param value:
         String or list of strings to be parsed and normalized.
+    :param regexp:
+        Compiled regular expression used to split the value when it is a
+        string.
+    :type regexp:
+        _sre.SRE_Pattern
     :returns:
         List of values with whitespace stripped.
     :rtype:
@@ -28,7 +34,7 @@ def parse_comma_separated_list(value):
         return []
 
     if not isinstance(value, (list, tuple)):
-        value = COMMA_SEPARATED_LIST_RE.split(value)
+        value = regexp.split(value)
 
     item_gen = (item.strip() for item in value)
     return [item for item in item_gen if item]

tests/unit/test_get_local_plugins.py

@@ -18,7 +18,10 @@ def test_get_local_plugins_respects_isolated():
 
 def test_get_local_plugins_uses_cli_config():
     """Verify behaviour of get_local_plugins with a specified config."""
+    config_obj = mock.Mock()
     config_finder = mock.MagicMock()
+    config_finder.cli_config.return_value = config_obj
+    config_obj.get.return_value = ''
 
     config.get_local_plugins(config_finder, cli_config='foo.ini')