Fix bug for plugins using extend_default_ignore

Since Flake8 3.0 we've had the ability for plugins to use
`extend_default_ignore` to register codes they want disabled by default.
This, however, was a permanent disabling unfortunately. Our code didn't
have a way of understanding that this new set of `ignore` codes was
actually the 'default' set for that run. Much like the
extended_select_list, we now attach extended_ignore_list to be able to
confidently determine if the ignore we get in the DecisionEngine is
actually the Default Ignore list and what plugins what us to ignore by
default.

Refs PyCQA/pep8-naming#157

src/flake8/options/aggregator.py

@@ -47,6 +47,10 @@ def aggregate_options(
     # Extend the default ignore value with the extended default ignore list,
     # registered by plugins.
     extended_default_ignore = manager.extended_default_ignore.copy()
+    # Let's store our extended default ignore for use by the decision engine
+    default_values.extended_default_ignore = (
+        manager.extended_default_ignore.copy()
+    )
     LOG.debug(
         "Extended default ignore list: %s", list(extended_default_ignore)
     )

src/flake8/style_guide.py

@@ -166,7 +166,9 @@ def __init__(self, options):  # type: (argparse.Namespace) -> None
                 reverse=True,
             )
         )
-        self.using_default_ignore = set(self.ignored) == set(defaults.IGNORE)
+        self.using_default_ignore = set(self.ignored) == set(
+            defaults.IGNORE
+        ).union(options.extended_default_ignore)
         self.using_default_select = set(self.selected) == set(defaults.SELECT)
 
     def _in_all_selected(self, code):  # type: (str) -> bool

tests/unit/test_decision_engine.py

@@ -10,6 +10,7 @@
 def create_options(**kwargs):
     """Create and return an instance of argparse.Namespace."""
     kwargs.setdefault('select', [])
+    kwargs.setdefault('extended_default_ignore', [])
     kwargs.setdefault('extended_default_select', [])
     kwargs.setdefault('ignore', [])
     kwargs.setdefault('extend_ignore', [])
@@ -144,54 +145,92 @@ def test_decision_for(select_list, ignore_list, extend_ignore, error_code,
 
 
 @pytest.mark.parametrize(
-    'select,ignore,extend_select,enabled_extensions,error_code,expected', [
-        (defaults.SELECT, [], ['I1'], [], 'I100',
+    'select,ignore,extended_default_ignore,extend_select,enabled_extensions,'
+    'error_code,expected', [
+        (defaults.SELECT, [], [], ['I1'], [], 'I100',
             style_guide.Decision.Selected),
-        (defaults.SELECT, [], ['I1'], [], 'I201',
+        (defaults.SELECT, [], [], ['I1'], [], 'I201',
             style_guide.Decision.Ignored),
-        (defaults.SELECT, ['I2'], ['I1'], [], 'I101',
+        (defaults.SELECT, ['I2'], [], ['I1'], [], 'I101',
             style_guide.Decision.Selected),
-        (defaults.SELECT, ['I2'], ['I1'], [], 'I201',
+        (defaults.SELECT, ['I2'], [], ['I1'], [], 'I201',
             style_guide.Decision.Ignored),
-        (defaults.SELECT, ['I1'], ['I10'], [], 'I101',
+        (defaults.SELECT, ['I1'], [], ['I10'], [], 'I101',
             style_guide.Decision.Selected),
-        (defaults.SELECT, ['I10'], ['I1'], [], 'I101',
+        (defaults.SELECT, ['I10'], [], ['I1'], [], 'I101',
             style_guide.Decision.Ignored),
-        (defaults.SELECT, [], [], ['U4'], 'U401',
+        (defaults.SELECT, [], [], [], ['U4'], 'U401',
             style_guide.Decision.Selected),
-        (defaults.SELECT, ['U401'], [], ['U4'], 'U401',
+        (defaults.SELECT, ['U401'], [], [], ['U4'], 'U401',
             style_guide.Decision.Ignored),
-        (defaults.SELECT, ['U401'], [], ['U4'], 'U402',
+        (defaults.SELECT, ['U401'], [], [], ['U4'], 'U402',
             style_guide.Decision.Selected),
-        (['E', 'W'], ['E13'], [], [], 'E131', style_guide.Decision.Ignored),
-        (['E', 'W'], ['E13'], [], [], 'E126', style_guide.Decision.Selected),
-        (['E2'], ['E21'], [], [], 'E221', style_guide.Decision.Selected),
-        (['E2'], ['E21'], [], [], 'E212', style_guide.Decision.Ignored),
-        (['F', 'W'], ['C90'], ['I1'], [], 'C901',
+        (
+            ['E', 'W'],
+            ['E13'],
+            [],
+            [],
+            [],
+            'E131',
+            style_guide.Decision.Ignored,
+        ),
+        (
+            ['E', 'W'],
+            ['E13'],
+            [],
+            [],
+            [],
+            'E126',
+            style_guide.Decision.Selected,
+        ),
+        (['E2'], ['E21'], [], [], [], 'E221', style_guide.Decision.Selected),
+        (['E2'], ['E21'], [], [], [], 'E212', style_guide.Decision.Ignored),
+        (['F', 'W'], ['C90'], [], ['I1'], [], 'C901',
             style_guide.Decision.Ignored),
-        (['E', 'W'], ['C'], [], [], 'E131',
+        (['E', 'W'], ['C'], [], [], [], 'E131',
             style_guide.Decision.Selected),
-        (defaults.SELECT, defaults.IGNORE, [], ['I'], 'I101',
+        (defaults.SELECT, defaults.IGNORE, [], [], ['I'], 'I101',
             style_guide.Decision.Selected),
-        (defaults.SELECT, defaults.IGNORE, ['G'], ['I'], 'G101',
+        (defaults.SELECT, defaults.IGNORE, [], ['G'], ['I'], 'G101',
             style_guide.Decision.Selected),
-        (defaults.SELECT, ['G1'], ['G'], ['I'], 'G101',
+        (defaults.SELECT, ['G1'], [], ['G'], ['I'], 'G101',
             style_guide.Decision.Ignored),
-        (defaults.SELECT, ['E126'], [], ['I'], 'I101',
+        (defaults.SELECT, ['E126'], [], [], ['I'], 'I101',
             style_guide.Decision.Selected),
-        (['E', 'W'], defaults.IGNORE, ['I'], [], 'I101',
+        (['E', 'W'], defaults.IGNORE, [], ['I'], [], 'I101',
             style_guide.Decision.Ignored),
+        (
+            ["E", "W", "I101"],
+            defaults.IGNORE + ("I101",),
+            ["I101"],
+            [],
+            [],
+            "I101",
+            style_guide.Decision.Selected,
+        ),
+        (
+            ["E", "W"],
+            defaults.IGNORE + ("I101",),
+            ["I101"],
+            [],
+            [],
+            "I101",
+            style_guide.Decision.Ignored,
+        ),
         # TODO(sigmavirus24) Figure out how to exercise the final catch-all
         # return statement
     ]
 )
-def test_more_specific_decision_for_logic(select, ignore, extend_select,
-                                          enabled_extensions, error_code,
-                                          expected):
+def test_more_specific_decision_for_logic(
+    select, ignore, extended_default_ignore, extend_select,
+    enabled_extensions, error_code,
+    expected,
+):
     """Verify the logic of DecisionEngine.more_specific_decision_for."""
     decider = style_guide.DecisionEngine(
         create_options(
             select=select, ignore=ignore,
+            extended_default_ignore=extended_default_ignore,
             extended_default_select=extend_select,
             enable_extensions=enabled_extensions,
         ),

tests/unit/test_style_guide.py

@@ -13,6 +13,7 @@
 def create_options(**kwargs):
     """Create and return an instance of argparse.Namespace."""
     kwargs.setdefault('select', [])
+    kwargs.setdefault('extended_default_ignore', [])
     kwargs.setdefault('extended_default_select', [])
     kwargs.setdefault('ignore', [])
     kwargs.setdefault('extend_ignore', [])