There is actually a question at the end. Your code does not account for the "case-insensitive" part.

Just checked and this is written in the initial setup:

-- # write your SQL statement here: you are given a table 'ispalindrome' with column 'str', return a table with column 'str' and your result in a column named 'res'.

Do you think this should be made more clear?

The description is shared across all languages. SQL setup is mostly like this that you have to write a SELECT query.
Normally this is stated in the solution setup. If it is not then indeed this should be added.

You should look where in your code you add the space and why it is not added in the "hello hello" case.

• Please add assertion failure messages writing the input.
• Please add leading and trailing spaces in fixed, sample, and random tests.

• Please also add possible leading and trailing spaces in fixed/sample tests (e.g. change to " double spaced words ")
• Please enclose the string in the headers by " like e.g. test("Test \"hello hello\"", () { ...

Added random tests to C#.

Your solution changes the order of characters and white space which it is not supposed to do. Not a kata issue.

You should consult the Python docs if you want to know why this happens.

Test case generation was updated now to only generate space-separated words without other whitespace.

Approved.

very clever indeed

Please add fixed/sample tests with leading/trainling white space.

Is it actually a requirement that all kinds of white space should be supported? I only read that spaces (0x20) should be retained and not trimmed/collapsed (like it would be with naive Haskell/Python solutions).

It is stated that 1--1 is valid and that an unary minus is not separated by a whitespace before parentheses. Your example follow these rules.