chess-project/fixtures

Tactical and Gambit Fixture Sets

This directory collects JSON fixtures for automated regression tests and training data generation. Each file contains narrowly scoped cases for a single tactical motif or gambit family so that Jest or other tooling can load them directly without hard-coding FEN strings in test suites.

File naming

• tactics/<pattern>.json – Examples for one tactical motif. Each file follows the same schema.
• gambits.json – Openings that should be recognised by move-sequence matching.

Common schema

Every tactical case shares the following shape:

{
  "patternType": "PIN",
  "description": "Short explanation of the motif and what the move achieves.",
  "cases": [
    {
      "id": "unique-string",
      "initialFen": "...",
      "sideToMove": "white",
      "bestMove": { "san": "Bb5", "uci": "f1b5" },
      "resultingFen": "...",
      "expectedPattern": {
        "type": "PIN",
        "side": "white",
        "attackerSquares": ["b5"],
        "targetSquares": ["c6"],
        "keySquares": ["e8"],
        "explanationKey": "pin_to_king"
      },
      "context": "Optional PGN fragment or free-text rationale.",
      "tags": ["opening", "classical"]
    }
  ]
}

This layout aligns with the TacticalPattern interface defined in the library contract and keeps enough metadata for round-trip testing: the move that produces the tactic, the resulting position, and the expected pattern payload.

Using the fixtures in tests

• Load the JSON files and iterate through cases to drive detectTactics, findTacticalOpportunitiesForSide, or higher-level exercise generators.
• The initialFen represents the position before the critical move is played.
• Apply bestMove to reach resultingFen, then assert that the reported pattern matches expectedPattern.

Adding more cases

When adding new fixtures, prefer minimal positions that isolate the intended motif so failures are easy to debug. Include a short context note so the scenario can be recreated or visualised quickly when a test fails.