split silently returns wrong result for multi-character separators

[Miladkhoshdel]

Repository commit

791deb4

Python version (python --version)

3.14.4

Dependencies version (pip freeze)

pip==26.0.1

Expected behavior

In strings/split.py, the custom split function should not silently return the unsplit string when separator has multiple characters. It should raise a clear ValueError.

Actual behavior

File location

strings/split.py

Actual behavior

In strings/split.py, the custom split function compares each character in the input string with separator.

Because of that, a multi-character separator such as "--" is never matched:

split("a--b--c", separator="--")

[Miladkhoshdel]

I opened a PR for this here: #14655