Test positions for debugging chess engines. Formatted as JSON array of FEN strings

Chess Perft test positions

[
   {
      "depth":1,
      "nodes":8,
      "fen":"r6r/1b2k1bq/8/8/7B/8/8/R3K2R b KQ - 3 2"
   },
   {
      "depth":1,
      "nodes":8,
      "fen":"8/8/8/2k5/2pP4/8/B7/4K3 b - d3 0 3"
   },
   {
      "depth":1,
      "nodes":19,
      "fen":"r1bqkbnr/pppppppp/n7/8/8/P7/1PPPPPPP/RNBQKBNR w KQkq - 2 2"
   },
   {
      "depth":1,
      "nodes":5,
      "fen":"r3k2r/p1pp1pb1/bn2Qnp1/2qPN3/1p2P3/2N5/PPPBBPPP/R3K2R b KQkq - 3 2"
   },
   {
      "depth":1,
      "nodes":44,
      "fen":"2kr3r/p1ppqpb1/bn2Qnp1/3PN3/1p2P3/2N5/PPPBBPPP/R3K2R b KQ - 3 2"
   },
   {
      "depth":1,
      "nodes":39,
      "fen":"rnb2k1r/pp1Pbppp/2p5/q7/2B5/8/PPPQNnPP/RNB1K2R w KQ - 3 9"
   },
   {
      "depth":1,
      "nodes":9,
      "fen":"2r5/3pk3/8/2P5/8/2K5/8/8 w - - 5 4"
   },
   {
      "depth":3,
      "nodes":62379,
      "fen":"rnbq1k1r/pp1Pbppp/2p5/8/2B5/8/PPP1NnPP/RNBQK2R w KQ - 1 8"
   },
   {
      "depth":3,
      "nodes":89890,
      "fen":"r4rk1/1pp1qppp/p1np1n2/2b1p1B1/2B1P1b1/P1NP1N2/1PP1QPPP/R4RK1 w - - 0 10"
   },
   {
      "depth":6,
      "nodes":1134888,
      "fen":"3k4/3p4/8/K1P4r/8/8/8/8 b - - 0 1"
   },
   {
      "depth":6,
      "nodes":1015133,
      "fen":"8/8/4k3/8/2p5/8/B2P2K1/8 w - - 0 1"
   },
   {
      "depth":6,
      "nodes":1440467,
      "fen":"8/8/1k6/2b5/2pP4/8/5K2/8 b - d3 0 1"
   },
   {
      "depth":6,
      "nodes":661072,
      "fen":"5k2/8/8/8/8/8/8/4K2R w K - 0 1"
   },
   {
      "depth":6,
      "nodes":803711,
      "fen":"3k4/8/8/8/8/8/8/R3K3 w Q - 0 1"
   },
   {
      "depth":4,
      "nodes":1274206,
      "fen":"r3k2r/1b4bq/8/8/8/8/7B/R3K2R w KQkq - 0 1"
   },
   {
      "depth":4,
      "nodes":1720476,
      "fen":"r3k2r/8/3Q4/8/8/5q2/8/R3K2R b KQkq - 0 1"
   },
   {
      "depth":6,
      "nodes":3821001,
      "fen":"2K2r2/4P3/8/8/8/8/8/3k4 w - - 0 1"
   },
   {
      "depth":5,
      "nodes":1004658,
      "fen":"8/8/1P2K3/8/2n5/1q6/8/5k2 b - - 0 1"
   },
   {
      "depth":6,
      "nodes":217342,
      "fen":"4k3/1P6/8/8/8/8/K7/8 w - - 0 1"
   },
   {
      "depth":6,
      "nodes":92683,
      "fen":"8/P1k5/K7/8/8/8/8/8 w - - 0 1"
   },
   {
      "depth":6,
      "nodes":2217,
      "fen":"K1k5/8/P7/8/8/8/8/8 w - - 0 1"
   },
   {
      "depth":7,
      "nodes":567584,
      "fen":"8/k1P5/8/1K6/8/8/8/8 w - - 0 1"
   },
   {
      "depth":4,
      "nodes":23527,
      "fen":"8/8/2k5/5q2/5n2/8/5K2/8 b - - 0 1"
   }
]

Some of the FEN notations are messed up. The order in which castling legality is specified must follow "KQkq": https://en.wikipedia.org/wiki/Forsyth–Edwards_Notation (In the german article this is explicitly stated). For example lichess won't recognize this otherwise.

Some of the FEN notations are messed up. The order in which castling legality is specified must follow "KQkq": https://en.wikipedia.org/wiki/Forsyth–Edwards_Notation (In the german article this is explicitly stated). For example lichess won't recognize this otherwise.

Fixed :)

8/8/8/2k5/2pP4/8/B7/4K3 b - d3 5 3 the pawn push that created the enpassant should have set the halfmoves to 0, my program was failing to load this position because of this (which I know is a problem in my end as my validator should be more relaxed, but just saying).

Thanks @ajax333221, fixed

Thank you! Those helped me find and fix a couple of bugs in my engine.

Very useful list, thankyou

this is great, thanks so much!

for anyone using this for testing, the following commands will convert this into a comma-delimited list of string literals, so you can stick them in an array or something.

SRC="https://gist.githubusercontent.com/peterellisjones/8c46c28141c162d1d8a0f0badbc9cff9/raw/b11af5a3dd978724ac2d4a531217133b9a3ad9ba/Chess%2520Perft%2520test%2520positions"

curl $SRC | jq ".[] | .fen" | sed "s/\$/,/g"

Thanks, this was very helpful for debugging my chess engine!