Issue 4044 - Added handling for __future__ unicode_literals import to check_quotes()

flake8-abp/flake8_abp.py

Index: flake8-abp/flake8_abp.py
===================================================================
--- a/flake8-abp/flake8_abp.py
+++ b/flake8-abp/flake8_abp.py
@@ -39,16 +39,18 @@
 }
 
 ESSENTIAL_BUILTINS = set(dir(builtins)) - {'apply', 'buffer', 'coerce',
                                            'intern', 'file'}
 
 LEAVE_BLOCK = (ast.Return, ast.Raise, ast.Continue, ast.Break)
 VOLATILE = object()
 
+is_unicode_literals = False
+
 
 def evaluate(node):
     try:
         return eval(compile(ast.Expression(node), '', 'eval'), {})
     except Exception:
         return VOLATILE
 
 
@@ -372,44 +374,61 @@
         return (0, 'A303 non-default file encoding')
 
 check_non_default_encoding.name = 'abp-non-default-encoding'
 check_non_default_encoding.version = __version__
 
 
 def check_quotes(logical_line, tokens, previous_logical):
     first_token = True
+    global is_unicode_literals
+
+    # check if this is beginning of file
+    if tokens[0][3][0] == 1:
+        is_unicode_literals = False
+
+    # check if in unicode_literals mode
+    token_strings = [t[1] for t in tokens]
+    if token_strings[:3] == ['from', '__future__', 'import']:
+        if 'unicode_literals' in token_strings:
+            is_unicode_literals = True
 
     for kind, token, start, end, _ in tokens:
         if kind == tokenize.INDENT or kind == tokenize.DEDENT:
             continue
 
         if kind == tokenize.STRING:
             match = re.search(r'^(u)?(b)?(r)?((""")?.*)$',
                               token, re.IGNORECASE | re.DOTALL)
             (is_unicode, is_bytes, is_raw,
              literal, has_doc_quotes) = match.groups()
 
             if first_token and re.search(r'^(?:(?:def|class)\s|$)',
                                          previous_logical):
                 if not has_doc_quotes:
                     yield (start, 'A109 use triple double '
                                   'quotes for docstrings')
-                elif is_unicode or is_bytes or is_raw:
-                    yield (start, "A109 don't use u'', b'' "
-                                  "or r'' for doc strings")
+                if is_raw:
+                    yield (start, 'A109 do not use "r" prefix for docstrings')
+                if is_unicode and not is_unicode_literals:
+                    yield (start, 'A112 use "from __future__ import'
+                                  'unicode_literals" instead of '
+                                  'prefixing literals with "u"')
             elif start[0] == end[0]:
                 if is_raw:
                     literal = re.sub(r'\\(?!{})'.format(literal[0]),
                                      '\\\\\\\\', literal)
-
+                if is_unicode and not is_unicode_literals:
+                    yield (start, 'A112 use "from __future__ import'
+                                  'unicode_literals" instead of '
+                                  'prefixing literals with "u"')
                 if sys.version_info[0] >= 3:
                     if is_bytes:
                         literal = 'b' + literal
-                elif is_unicode:
+                elif not is_bytes:
                     literal = 'u' + literal
 
                 if ascii(eval(literal)) != literal:
                     yield (start, "A110 string literal doesn't match "
                                   '{}()'.format(ascii.__name__))
 
         first_token = False