fix from review.

flake8_eradicate.py

@@ -1,7 +1,8 @@
 # -*- coding: utf-8 -*-
 
+import ast
 import tokenize
-from typing import Iterable, Tuple
+from typing import Iterable, Iterator, Tuple, Type
 
 import pkg_resources
 from eradicate import Eradicator
@@ -25,7 +26,15 @@ class Checker(object):
 
     options = None
 
-    def __init__(self, tree, filename: str):    # noqa: D107
+    def __init__(self, tree: ast.AST, filename: str):
+        """
+        ``flake8`` plugin constructor.
+
+        Arguments:
+            tree: the file abstract syntax tree.
+            filename: the name of the file to process
+
+        """
         self.filename = filename
 
         self._options = {
@@ -98,7 +107,7 @@ def parse_options(cls, options) -> None:
         """Parses registered options for providing them to each visitor."""
         cls.options = options
 
-    def run(self) -> Iterable[Tuple[int, str]]:
+    def run(self) -> Iterator[Tuple[int, int, str, Type['Checker']]]:
         """Runs on each step of flake8."""
         for line_no in self._lines_with_commented_out_code():
             yield line_no, 0, self._error_template, type(self)
@@ -118,14 +127,20 @@ def _lines_with_commented_out_code(self) -> Iterable[int]:
         when the tokens indicate a comment in the physical line.
         """
         with open(self.filename) as f:
+            # Skip python commented encoding line
+            first_line = f.readline()
+            if not first_line.startswith('# -*- coding: utf-8 -*-'):
+                # rewind as we don't want to skip it during tokenization
+                f.seek(0)
+
             file_tokens = tokenize.generate_tokens(f.readline)
             comment_in_file = any(
                 token.type == tokenize.COMMENT
                 for token in file_tokens
             )
 
             if comment_in_file:
-                f.seek(0)   # rewind file
+                f.seek(0)
                 for line_no, line in enumerate(f.readlines(), start=1):
                     filtered_source = ''.join(
                         self._eradicator.filter_commented_out_code(

tests/fixtures/correct_no_comment.py

@@ -0,0 +1,16 @@
+# -*- coding: utf-8 -*-
+
+class Some(object):
+
+    property_name = 1
+
+    other_property: int = 2
+
+    def some_method(self) -> None:
+        print('not True and not False')
+
+        print(12 + 23 / 3)
+
+
+def some_function():
+    return "something"

tests/test_comments.py

@@ -136,12 +136,12 @@ def test_lines_with_commented_out_code_incorrect_fixture_output(absolute_path):
 
     OptionsStub = namedtuple(
         'Options',
-        'eradicate_aggressive eradicate_whitelist eradicate_whitelist_extend'
+        'eradicate_aggressive eradicate_whitelist eradicate_whitelist_extend',
     )
     Checker.options = OptionsStub(
         eradicate_aggressive=True,
         eradicate_whitelist=False,
-        eradicate_whitelist_extend=False
+        eradicate_whitelist_extend=False,
     )
 
     checker = Checker(tree=None, filename=filename)
@@ -150,3 +150,24 @@ def test_lines_with_commented_out_code_incorrect_fixture_output(absolute_path):
         assert output == [3, 4, 9, 10, 14, 15, 16, 18, 19, 21, 22, 24, 25]
     else:
         assert output == [3, 9, 10, 14, 15, 16, 18, 19, 21, 22, 24, 25]
+
+
+def test_lines_with_commented_out_code_file_without_comment_output(
+    absolute_path,
+):
+    """Verify central underlying method is returning correct output."""
+    filename = absolute_path('fixtures', 'correct_no_comment.py')
+
+    OptionsStub = namedtuple(
+        'Options',
+        'eradicate_aggressive eradicate_whitelist eradicate_whitelist_extend',
+    )
+    Checker.options = OptionsStub(
+        eradicate_aggressive=True,
+        eradicate_whitelist=False,
+        eradicate_whitelist_extend=False,
+    )
+
+    checker = Checker(tree=None, filename=filename)
+    output = list(checker._lines_with_commented_out_code())
+    assert output == []