Really great kata of the chess series to solve, thanks to the author for that.

I was considering that however I think this would lead to problems on whether it needs to be simultaneous or not, I think the "or" here is better for clarity.

on the first rank (bottom row) and the eighth rank (top row).

This sounds as if there need to be pawns in BOTH ranks for it to be considered invalid. I think after the first "or" was changed to "and" it's clear enough and changing the second "or" will cause more misunderstandings than solve them. If more people ask for this though, I will change it.

on the first rank (bottom row) or the eighth rank (top row).

Change "or" to "and" here as well.

Resolved

Pawns (P or p) can’t be on the first rank (bottom row) or the eighth rank (top row).

As Iygzounette pointed out, this part of the rules should change "or" to "and". Not every solver is into chess at the end of the day.

I see you're not a chess amateur. Let me briefly explain why that is the case:

The white pawns cannot be on the 1st rank and the black pawn cannot be on the 8th rank, as said in the description. However, the case with opposite pawns is simply impossible, 'cause according to the rules of chess, when a pawn reaches an opposite side of the board (for white pawns - 8th rank and the for black pawns - 1st rank), it must promote to a major piece (queen, rook, bishop or knight).

Though, I think the author should add this part to the description. Good point by you.

Cool kata, but you should add clear error messages. For exemple, at first I didn't know if 'Pawns (P or p) can’t be on the first rank (bottom row) or the eighth rank (top row).' meant that both "P" and "p" couldn't be on either ranks or if only "P" couldn't be on the first rank and vice-versa. This isn't a major issue but since I had to do a complete debug before realizing I had misunderstood, I think that adding clear error messages would help more than one (but maybe it would make your kata easier and you don't want that).

Oh right sorry haha, thanks!

Return literally the string "Invalid".

What is 'Invalid' in Python? Do I just return False?

Done, thanks

hi,

In the description, in the validity checks, the last point should be suppressed (redundant with the first one).

Should be good now I think

Language agnostic doesn't usually mean separate code blocks, it means generic for all languages.

Resolved