blind_chess/packages/server/test/unit/view.test.ts

import { describe, it, expect } from 'vitest';
import { Chess } from 'chess.js';
import { buildView, ownSquares } from '../../src/view.js';
import type { Game } from '../../src/state.js';
import { RATE_LIMIT } from '../../src/state.js';

function makeGame(mode: 'blind' | 'vanilla', fen?: string, status: 'active' | 'finished' = 'active'): Game {
  return {
    id: 'testtest',
    mode,
    highlightingEnabled: false,
    status,
    createdAt: Date.now(),
    chess: fen ? new Chess(fen) : new Chess(),
    moveHistory: [],
    announcements: [],
    players: {
      w: { token: 'w'.repeat(24), socket: null, joinedAt: 0, rateBucket: { tokens: RATE_LIMIT.capacity, last: 0 } },
      b: { token: 'b'.repeat(24), socket: null, joinedAt: 0, rateBucket: { tokens: RATE_LIMIT.capacity, last: 0 } },
    },
    armed: null,
    drawOffer: null,
    disconnectAt: {},
  };
}

describe('buildView: security boundary', () => {
  it('blind/active white view contains zero black pieces', () => {
    const g = makeGame('blind');
    const view = buildView(g, 'w');
    for (const piece of Object.values(view.pieces)) {
      expect(piece?.color).toBe('w');
    }
    expect(Object.keys(view.pieces).length).toBe(16); // all 16 white pieces
  });

  it('blind/active black view contains zero white pieces', () => {
    const g = makeGame('blind');
    const view = buildView(g, 'b');
    for (const piece of Object.values(view.pieces)) {
      expect(piece?.color).toBe('b');
    }
    expect(Object.keys(view.pieces).length).toBe(16);
  });

  it('vanilla/active shows both colors', () => {
    const g = makeGame('vanilla');
    const view = buildView(g, 'w');
    expect(Object.keys(view.pieces).length).toBe(32);
  });

  it('blind/finished reveals both colors (post-game review)', () => {
    const g = makeGame('blind', undefined, 'finished');
    const view = buildView(g, 'w');
    expect(Object.keys(view.pieces).length).toBe(32);
  });

  it('blind: inCheck is null for non-actor (info leak prevention)', () => {
    // Black to move and is in check. White's view says null (it's not white's turn,
    // and revealing inCheck-status of opponent leaks info).
    const g = makeGame('blind', 'rnb1kbnr/pppp1ppp/8/4p3/6Pq/5P2/PPPPP2P/RNBQKBNR w KQkq - 1 3');
    const view = buildView(g, 'b');
    // It's white's turn here. Black viewer is not the to-move side.
    expect(view.inCheck).toBeNull();
  });
});

describe('ownSquares', () => {
  it('starting position returns 16 own squares', () => {
    const g = makeGame('blind');
    expect(ownSquares(g, 'w').size).toBe(16);
    expect(ownSquares(g, 'b').size).toBe(16);
  });

  it('contains only own-color squares', () => {
    const g = makeGame('blind');
    const wSet = ownSquares(g, 'w');
    expect(wSet.has('e2')).toBe(true);
    expect(wSet.has('e7')).toBe(false);
  });
});