Add --replace-single-quotes to replace single quotes with double ones

README.md

@@ -112,6 +112,7 @@ Checks for the existence of private keys.
 
 #### `double-quote-string-fixer`
 This hook replaces double quoted strings with single quoted strings.
+  - `--replace-single-quotes` - replaces single quoted strings with double quoted strings.
 
 #### `end-of-file-fixer`
 Makes sure files end in a newline and only a newline.

pre_commit_hooks/string_fixer.py

@@ -13,10 +13,10 @@
 else:  # pragma: <3.12 cover
     FSTRING_START = FSTRING_END = -1
 
-START_QUOTE_RE = re.compile('^[a-zA-Z]*"')
+START_QUOTE_RE = re.compile("^[a-zA-Z]*['\"]")
 
 
-def handle_match(token_text: str) -> str:
+def handle_match(token_text: str, replace_single_quotes: bool = False) -> str:
     if '"""' in token_text or "'''" in token_text:
         return token_text
 
@@ -25,9 +25,11 @@ def handle_match(token_text: str) -> str:
         meat = token_text[match.end():-1]
         if '"' in meat or "'" in meat:
             return token_text
+        elif replace_single_quotes:
+            return match.group().replace("'", '"') + meat + '"'
         else:
             return match.group().replace('"', "'") + meat + "'"
-    else:
+    else:  # will this happen?  # pragma: no cover
         return token_text
 
 
@@ -39,7 +41,7 @@ def get_line_offsets_by_line_no(src: str) -> list[int]:
     return offsets
 
 
-def fix_strings(filename: str) -> int:
+def fix_strings(filename: str, replace_single_quotes: bool = False) -> int:
     with open(filename, encoding='UTF-8', newline='') as f:
         contents = f.read()
     line_offsets = get_line_offsets_by_line_no(contents)
@@ -58,7 +60,9 @@ def fix_strings(filename: str) -> int:
         elif token_type == FSTRING_END:  # pragma: >=3.12 cover
             fstring_depth -= 1
         elif fstring_depth == 0 and token_type == tokenize.STRING:
-            new_text = handle_match(token_text)
+            new_text = handle_match(
+                token_text, replace_single_quotes=replace_single_quotes
+            )
             splitcontents[
                 line_offsets[srow] + scol:
                 line_offsets[erow] + ecol
@@ -76,12 +80,20 @@ def fix_strings(filename: str) -> int:
 def main(argv: Sequence[str] | None = None) -> int:
     parser = argparse.ArgumentParser()
     parser.add_argument('filenames', nargs='*', help='Filenames to fix')
+    parser.add_argument(
+        '--replace-single-quotes',
+        action='store_true',
+        default=False,
+        help='Replace single quotes into double quotes',
+    )
     args = parser.parse_args(argv)
 
     retv = 0
 
     for filename in args.filenames:
-        return_value = fix_strings(filename)
+        return_value = fix_strings(
+            filename, replace_single_quotes=args.replace_single_quotes
+        )
         if return_value != 0:
             print(f'Fixing strings in {filename}')
         retv |= return_value

tests/string_fixer_test.py

@@ -8,17 +8,20 @@
 
 TESTS = (
     # Base cases
-    ("''", "''", 0),
-    ('""', "''", 1),
-    (r'"\'"', r'"\'"', 0),
-    (r'"\""', r'"\""', 0),
-    (r"'\"\"'", r"'\"\"'", 0),
+    ("''", "''", False, 0),
+    ("''", '""', True, 1),
+    ('""', "''", False, 1),
+    ('""', '""', True, 0),
+    (r'"\'"', r'"\'"', False, 0),
+    (r'"\""', r'"\""', False, 0),
+    (r"'\"\"'", r"'\"\"'", False, 0),
     # String somewhere in the line
-    ('x = "foo"', "x = 'foo'", 1),
+    ('x = "foo"', "x = 'foo'", False, 1),
+    ("x = 'foo'", 'x = "foo"', True, 1),
     # Test escaped characters
-    (r'"\'"', r'"\'"', 0),
+    (r'"\'"', r'"\'"', False, 0),
     # Docstring
-    ('""" Foo """', '""" Foo """', 0),
+    ('""" Foo """', '""" Foo """', False, 0),
     (
         textwrap.dedent(
             """
@@ -34,23 +37,51 @@
         '\n
         """,
         ),
+        False,
         1,
     ),
-    ('"foo""bar"', "'foo''bar'", 1),
+    (
+        textwrap.dedent(
+            """
+        x = ' \\
+        foo \\
+        '\n
+        """,
+        ),
+        textwrap.dedent(
+            """
+        x = " \\
+        foo \\
+        "\n
+        """,
+        ),
+        True,
+        1,
+    ),
+    ('"foo""bar"', "'foo''bar'", False, 1),
+    ("'foo''bar'", '"foo""bar"', True, 1),
     pytest.param(
         "f'hello{\"world\"}'",
         "f'hello{\"world\"}'",
+        False,
         0,
         id='ignore nested fstrings',
     ),
 )
 
 
-@pytest.mark.parametrize(('input_s', 'output', 'expected_retval'), TESTS)
-def test_rewrite(input_s, output, expected_retval, tmpdir):
+@pytest.mark.parametrize(
+    ('input_s', 'output', 'reversed_case', 'expected_retval'), TESTS
+)
+def test_rewrite(input_s, output, reversed_case, expected_retval, tmpdir):
     path = tmpdir.join('file.py')
     path.write(input_s)
-    retval = main([str(path)])
+
+    argv = [str(path)]
+    if reversed_case:
+        argv.append("--replace-single-quotes")
+    retval = main(argv)
+
     assert path.read() == output
     assert retval == expected_retval