Move the NotChecker to its own file

2 files changed, 91 insertions, 79 deletions

diff --git a/pylint/checkers/refactoring/__init__.py b/pylint/checkers/refactoring/__init__.py
index 9a66a71e7..3fded2a3e 100644
--- a/pylint/checkers/refactoring/__init__.py
+++ b/pylint/checkers/refactoring/__init__.py
@@ -34,7 +34,7 @@
 # For details: https://github.com/PyCQA/pylint/blob/master/COPYING
 
 """Looks for code which can be refactored."""
-import builtins
+
 import collections
 import copy
 import itertools
@@ -48,6 +48,7 @@ from astroid import decorators
 from pylint import checkers, interfaces
 from pylint import utils as lint_utils
 from pylint.checkers import utils
+from pylint.checkers.refactoring.not_checker import NotChecker
 from pylint.checkers.utils import node_frame_class
 
 KNOWN_INFINITE_ITERATORS = {"itertools.count"}
@@ -1514,84 +1515,6 @@ class RecommandationChecker(checkers.BaseChecker):
                 return
 
 
-class NotChecker(checkers.BaseChecker):
-    """checks for too many not in comparison expressions
-
-    - "not not" should trigger a warning
-    - "not" followed by a comparison should trigger a warning
-    """
-
-    __implements__ = (interfaces.IAstroidChecker,)
-    msgs = {
-        "C0113": (
-            'Consider changing "%s" to "%s"',
-            "unneeded-not",
-            "Used when a boolean expression contains an unneeded negation.",
-        )
-    }
-    name = "refactoring"
-    reverse_op = {
-        "<": ">=",
-        "<=": ">",
-        ">": "<=",
-        ">=": "<",
-        "==": "!=",
-        "!=": "==",
-        "in": "not in",
-        "is": "is not",
-    }
-    # sets are not ordered, so for example "not set(LEFT_VALS) <= set(RIGHT_VALS)" is
-    # not equivalent to "set(LEFT_VALS) > set(RIGHT_VALS)"
-    skipped_nodes = (astroid.Set,)
-    # 'builtins' py3, '__builtin__' py2
-    skipped_classnames = [
-        "%s.%s" % (builtins.__name__, qname) for qname in ("set", "frozenset")
-    ]
-
-    @utils.check_messages("unneeded-not")
-    def visit_unaryop(self, node):
-        if node.op != "not":
-            return
-        operand = node.operand
-
-        if isinstance(operand, astroid.UnaryOp) and operand.op == "not":
-            self.add_message(
-                "unneeded-not",
-                node=node,
-                args=(node.as_string(), operand.operand.as_string()),
-            )
-        elif isinstance(operand, astroid.Compare):
-            left = operand.left
-            # ignore multiple comparisons
-            if len(operand.ops) > 1:
-                return
-            operator, right = operand.ops[0]
-            if operator not in self.reverse_op:
-                return
-            # Ignore __ne__ as function of __eq__
-            frame = node.frame()
-            if frame.name == "__ne__" and operator == "==":
-                return
-            for _type in (utils.node_type(left), utils.node_type(right)):
-                if not _type:
-                    return
-                if isinstance(_type, self.skipped_nodes):
-                    return
-                if (
-                    isinstance(_type, astroid.Instance)
-                    and _type.qname() in self.skipped_classnames
-                ):
-                    return
-            suggestion = "%s %s %s" % (
-                left.as_string(),
-                self.reverse_op[operator],
-                right.as_string(),
-            )
-            self.add_message(
-                "unneeded-not", node=node, args=(node.as_string(), suggestion)
-            )
-
-
 class LenChecker(checkers.BaseChecker):
     """Checks for incorrect usage of len() inside conditions.
     Pep8 states:
diff --git a/pylint/checkers/refactoring/not_checker.py b/pylint/checkers/refactoring/not_checker.py
new file mode 100644
index 000000000..95cee4b2d
--- /dev/null
+++ b/pylint/checkers/refactoring/not_checker.py
@@ -0,0 +1,89 @@
+# -*- coding: utf-8 -*-
+
+# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+# For details: https://github.com/PyCQA/pylint/blob/master/COPYING
+
+import builtins
+
+import astroid
+
+from pylint import checkers, interfaces
+from pylint.checkers import utils
+
+
+class NotChecker(checkers.BaseChecker):
+    """checks for too many not in comparison expressions
+
+    - "not not" should trigger a warning
+    - "not" followed by a comparison should trigger a warning
+    """
+
+    __implements__ = (interfaces.IAstroidChecker,)
+    msgs = {
+        "C0113": (
+            'Consider changing "%s" to "%s"',
+            "unneeded-not",
+            "Used when a boolean expression contains an unneeded negation.",
+        )
+    }
+    name = "refactoring"
+    reverse_op = {
+        "<": ">=",
+        "<=": ">",
+        ">": "<=",
+        ">=": "<",
+        "==": "!=",
+        "!=": "==",
+        "in": "not in",
+        "is": "is not",
+    }
+    # sets are not ordered, so for example "not set(LEFT_VALS) <= set(RIGHT_VALS)" is
+    # not equivalent to "set(LEFT_VALS) > set(RIGHT_VALS)"
+    skipped_nodes = (astroid.Set,)
+    # 'builtins' py3, '__builtin__' py2
+    skipped_classnames = [
+        "%s.%s" % (builtins.__name__, qname) for qname in ("set", "frozenset")
+    ]
+
+    @utils.check_messages("unneeded-not")
+    def visit_unaryop(self, node):
+        if node.op != "not":
+            return
+        operand = node.operand
+
+        if isinstance(operand, astroid.UnaryOp) and operand.op == "not":
+            self.add_message(
+                "unneeded-not",
+                node=node,
+                args=(node.as_string(), operand.operand.as_string()),
+            )
+        elif isinstance(operand, astroid.Compare):
+            left = operand.left
+            # ignore multiple comparisons
+            if len(operand.ops) > 1:
+                return
+            operator, right = operand.ops[0]
+            if operator not in self.reverse_op:
+                return
+            # Ignore __ne__ as function of __eq__
+            frame = node.frame()
+            if frame.name == "__ne__" and operator == "==":
+                return
+            for _type in (utils.node_type(left), utils.node_type(right)):
+                if not _type:
+                    return
+                if isinstance(_type, self.skipped_nodes):
+                    return
+                if (
+                    isinstance(_type, astroid.Instance)
+                    and _type.qname() in self.skipped_classnames
+                ):
+                    return
+            suggestion = "%s %s %s" % (
+                left.as_string(),
+                self.reverse_op[operator],
+                right.as_string(),
+            )
+            self.add_message(
+                "unneeded-not", node=node, args=(node.as_string(), suggestion)
+            )