CI: Add test case for unwanted patterns

ci/code_checks.sh

@@ -100,6 +100,14 @@ if [[ -z "$CHECK" || "$CHECK" == "lint" ]]; then
     cpplint --quiet --extensions=c,h --headers=h --recursive --filter=-readability/casting,-runtime/int,-build/include_subdir pandas/_libs/src/*.h pandas/_libs/src/parser pandas/_libs/ujson pandas/_libs/tslibs/src/datetime pandas/_libs/*.cpp
     RET=$(($RET + $?)) ; echo $MSG "DONE"
 
+    MSG='Check for use of not concatenated strings' ; echo $MSG
+    if [[ "$GITHUB_ACTIONS" == "true" ]]; then
+        $BASE_DIR/scripts/validate_string_concatenation.py --format="[error]{source_path}:{line_number}:{msg}" .
+    else
+        $BASE_DIR/scripts/validate_string_concatenation.py .
+    fi
+    RET=$(($RET + $?)) ; echo $MSG "DONE"
+
     echo "isort --version-number"
     isort --version-number
 

scripts/validate_string_concatenation.py

@@ -0,0 +1,129 @@
+#!/usr/bin/env python
+"""
+GH #30454
+
+Check where there is a string that needs to be concatenated.
+
+This is necessary after black formating,
+where for example black transforms this:
+
+>>> foo = (
+...         "bar "
+...         "baz"
+...     )
+
+into this:
+
+>>> foo = ("bar " "baz")
+
+Black is not considering this as an
+issue (see issue https://github.com/psf/black/issues/1051),
+so we are checking it here.
+"""
+
+import argparse
+import os
+import sys
+import token
+import tokenize
+from typing import Generator, List, Tuple
+
+FILE_EXTENSIONS_TO_CHECK = (".py", ".pyx", ".pyx.ini", ".pxd")
+
+
+def main(source_path: str, output_format: str) -> bool:
+    """
+    Main entry point of the script.
+
+    Parameters
+    ----------
+    source_path : str
+        Source path representing path to a file/directory.
+    output_format : str
+        Output format of the script.
+
+    Returns
+    -------
+    bool
+        True if found any strings that needs to be concatenated.
+
+    Raises
+    ------
+    ValueError
+        If the `source_path` is not pointing to existing file/directory.
+    """
+    if not os.path.exists(source_path):
+        raise ValueError(
+            "Please enter a valid path, pointing to a valid file/directory."
+        )
+
+    is_failed: bool = False
+
+    msg = "String unnecessarily split in two by black. Please merge them manually."
+
+    if os.path.isfile(source_path):
+        for source_path, line_number in strings_to_concatenate(source_path):
+            is_failed = True
+            print(
+                output_format.format(
+                    source_path=source_path, line_number=line_number, msg=msg
+                )
+            )
+
+    for subdir, _, files in os.walk(source_path):
+        for file_name in files:
+            if any(
+                file_name.endswith(extension) for extension in FILE_EXTENSIONS_TO_CHECK
+            ):
+                for source_path, line_number in strings_to_concatenate(
+                    os.path.join(subdir, file_name)
+                ):
+                    is_failed = True
+                    print(
+                        output_format.format(
+                            source_path=source_path, line_number=line_number, msg=msg
+                        )
+                    )
+    return is_failed
+
+
+def strings_to_concatenate(source_path: str) -> Generator[Tuple[str, int], None, None]:
+    """
+    Yielding the strings that needs to be concatenated in a given file.
+
+    Parameters
+    ----------
+    source_path : str
+        File path pointing to a single file.
+
+    Yields
+    ------
+    source_path : str
+        Source file path.
+    line_number : int
+        Line number of unconcatenated string.
+    """
+    with open(source_path, "r") as file_name:
+        tokens: List = list(tokenize.generate_tokens(file_name.readline))
+
+    for current_token, next_token in zip(tokens, tokens[1:]):
+        if current_token[0] == next_token[0] == token.STRING:
+            yield source_path, current_token[2][0]
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Validate concatenated strings")
+
+    parser.add_argument(
+        "path", nargs="?", default=".", help="Source path of file/directory to check."
+    )
+    parser.add_argument(
+        "--format",
+        "-f",
+        default="{source_path}:{line_number}:{msg}",
+        help="Output format of the unconcatenated strings.",
+    )
+
+    args = parser.parse_args()
+
+    sys.exit(main(source_path=args.path, output_format=args.format))