Merge pull request #111 from felixvd/add-import-shadowing

Add rule for import shadowing

README.rst

@@ -86,6 +86,21 @@ Requirements
 - Python 3.8, 3.9, 3.10, 3.11, and pypy3
 - flake8
 
+Rules
+-----
+
+A001:
+  A variable is shadowing a Python builtin.
+
+A002:
+  An argument is shadowing a Python builtin.
+
+A003:
+  A class attribute is shadowing a Python builtin.
+
+A004:
+  An import statement is shadowing a Python builtin.
+
 License
 -------
 GPL 2.0

flake8_builtins.py

@@ -14,9 +14,10 @@
 class BuiltinsChecker:
     name = 'flake8_builtins'
     version = '1.5.2'
-    assign_msg = 'A001 variable "{0}" is shadowing a python builtin'
-    argument_msg = 'A002 argument "{0}" is shadowing a python builtin'
-    class_attribute_msg = 'A003 class attribute "{0}" is shadowing a python builtin'
+    assign_msg = 'A001 variable "{0}" is shadowing a Python builtin'
+    argument_msg = 'A002 argument "{0}" is shadowing a Python builtin'
+    class_attribute_msg = 'A003 class attribute "{0}" is shadowing a Python builtin'
+    import_msg = 'A004 import statement "{0}" is shadowing a Python builtin'
 
     names = []
     ignore_list = {
@@ -223,8 +224,17 @@ def check_comprehension(self, statement):
 
     def check_import(self, statement):
         for name in statement.names:
-            if name.asname in self.names:
-                yield self.error(statement, variable=name.asname)
+            collision = None
+            if name.name in self.names and name.asname is None:
+                collision = name.name
+            elif name.asname in self.names:
+                collision = name.asname
+            if collision:
+                yield self.error(
+                    statement,
+                    message=self.import_msg,
+                    variable=collision,
+                )
 
     def check_class(self, statement):
         if statement.name in self.names:

run_tests.py

@@ -147,7 +147,6 @@ def bla(dict=3):
         b = 4"""
     check_code(source, 'A002')
 
-
 def test_kwonly_argument_message():
     source = """
     def bla(*, list):
@@ -357,21 +356,31 @@ def test_list_comprehension_multiple_as_list():
     check_code(source, 'A001')
 
 
+def test_import():
+    source = """from numpy import max"""
+    check_code(source, 'A004')
+
+
 def test_import_as():
     source = 'import zope.component.getSite as int'
-    check_code(source, 'A001')
+    check_code(source, 'A004')
 
 
 def test_import_from_as():
     source = 'from zope.component import getSite as int'
-    check_code(source, 'A001')
+    check_code(source, 'A004')
 
 
 def test_import_as_nothing():
     source = 'import zope.component.getSite as something_else'
     check_code(source)
 
 
+def test_import_collision_as_nothing():
+    source = """from numpy import max as non_shadowing_max"""
+    check_code(source)
+
+
 def test_import_from_as_nothing():
     source = 'from zope.component import getSite as something_else'
     check_code(source)