configparser: whitespace not stripped when writing empty values

Bug description:

When writing a configparser.ConfigParser to a file, keys with an empty value add a whitespace at the end of the line.

Eg. a line key = , ending with a whitespace.

import configparser
config = configparser.ConfigParser()
config["DEFAULT"] = {'ok': 'value', 'error': ''}
with open("test.ini", "w") as fhandle:
    config.write(fhandle)

Now the contents of test.ini are:

[DEFAULT]
ok = value
error = 

The line with the key "error" ends in a space. It appears the extra whitespace is introduced in ConfigParser.write(). Whitespaces are added to the delimiter, but this does not account for empty values.

class ConfigParser:
    def write(self, fp, space_around_delimiters=True):
        if space_around_delimiters:
            d = " {} ".format(self._delimiters[0])
        ...

Stripping the whitespace of the value in ConfigParser._write_section() solves this.

class ConfigParser:
    def _write_section(self, fp, section_name, section_items, delimiter, unnamed=False):
        if not unnamed:
            fp.write(f"[{section_name}]\n")
        for key, value in section_items:
            self._validate_key_contents(key)
            value = self._interpolation.before_write(
                self, section_name, key, value
            )
            if value is not None or not self._allow_no_value:
                # Convert all possible line-endings into '\n\t'
                value = (delimiter + str(value).replace('\r\n', '\n')
                         .replace('\r', '\n').replace('\n', '\n\t'))
            else:
                value = ""
            # Change from the original: strip empty space to avoid "key = " for
            # empty keys!!!
            line = f"{key}{value}".strip(" ")
            fp.write(f"{line}\n")
            # Done with changes.
        fp.write("\n")

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs

• gh-157467

ConfigParser.write() と _write_section() から始めます。issue では、これらが末尾の空白を導入するエントリポイントとして特定されています。空の値を書き込む場合のカバレッジを追加し、生成された INI 行に末尾の空白がないことを確認してから、関連する configparser テストを実行します。リンクされた PR はすでに issue に記載されています。