Fix #16, avoid false positive when bad builtin overwritten by import

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- False positive when bad builtin is overwritten by import (#16)
 
 ## [0.6.0] - 2019-08-12
 ### Added

dlint/linters/base.py

@@ -10,6 +10,8 @@
 import ast
 import collections
 
+from .. import namespace
+
 Flake8Result = collections.namedtuple(
     'Flake8Result',
     ['lineno', 'col_offset', 'message']
@@ -19,9 +21,19 @@
 class BaseLinter(ast.NodeVisitor):
     def __init__(self, *args, **kwargs):
         self.results = []
+        self.namespace = None
 
         super(BaseLinter, self).__init__(*args, **kwargs)
 
     def get_results(self):
 
         return self.results
+
+    def visit(self, node):
+        if not self.namespace:
+            # Assuming that 'visit' is always called the first time with 'node'
+            # as an ast.Module. If not, we should fail fast with a raised
+            # exception and investigate.
+            self.namespace = namespace.Namespace.from_module_node(node)
+
+        super(BaseLinter, self).visit(node)

dlint/linters/helpers/bad_builtin_use.py

@@ -25,7 +25,8 @@ def illegal_builtin(self):
         """
 
     def visit_Name(self, node):
-        if node.id == self.illegal_builtin:
+        if (node.id == self.illegal_builtin
+                and not self.namespace.name_imported(node.id)):
             self.results.append(
                 base.Flake8Result(
                     lineno=node.lineno,

tests/test_helpers/test_bad_builtin_use.py

@@ -63,6 +63,23 @@ def test_bad_builtin_usage(self):
 
         assert result == expected
 
+    def test_bad_builtin_overwritten(self):
+        python_string = self.get_ast_node(
+            """
+            from foo import bar
+
+            result = bar()
+            """
+        )
+
+        linter = get_builtin_use_implementation('bar')
+        linter.visit(python_string)
+
+        result = linter.get_results()
+        expected = []
+
+        assert result == expected
+
     def test_no_builtin_usage(self):
         python_string = self.get_ast_node(
             """