claude (duplicate_chess)
32 lines
1.3 KiB
TypeScript
32 lines
1.3 KiB
TypeScript
import { describe, it, expect } from 'vitest';
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import { DuplicateGame } from './game';
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import { playSymmetric } from './test-helpers';
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import { ghosts } from './ghosts';
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describe('ghosts', () => {
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it('reports no ghosts at the start', () => {
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expect(ghosts(new DuplicateGame())).toEqual([]);
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});
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it('forms a ghost when a piece is captured on one board but not its twin', () => {
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const g = new DuplicateGame();
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// Symmetric opening so all four boards stay identical...
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playSymmetric(g, [
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[{ from: 'e2', to: 'e4' }, { from: 'e7', to: 'e5' }],
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[{ from: 'g1', to: 'f3' }, { from: 'b8', to: 'c6' }],
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]);
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// ...then North & South each play Nxe5 (capturing the e5 pawn),
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// and East captures that knight only on its boards (NE, SE).
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g.applyMove({ from: 'f3', to: 'e5' }); // N: Nf3xe5 on NW, NE
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g.applyMove({ from: 'f3', to: 'e5' }); // S: Nf3xe5 on SW, SE
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g.applyMove({ from: 'c6', to: 'e5' }); // E: Nc6xe5 on NE, SE — captures the white knight
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// North's knight on e5 survives on NW but was captured on NE -> NW/e5 is a ghost.
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// South's knight on e5 survives on SW but was captured on SE -> SW/e5 is a ghost.
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const result = ghosts(g).sort((x, y) => (x.board < y.board ? -1 : 1));
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expect(result).toEqual([
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{ board: 'NW', square: 'e5' },
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{ board: 'SW', square: 'e5' },
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]);
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});
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});
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