test(01-02): add failing tests for Tile model class

- Tests for constructor with id, type, position
- Tests for emoji getter returning correct emoji
- Tests for isAdjacent() method with various positions
- Tests for readonly properties and cleared default

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/__tests__/Tile.test.ts

@@ -0,0 +1,123 @@
+// src/__tests__/Tile.test.ts - Unit tests for Tile model class
+import { describe, it, expect } from 'vitest';
+import { Tile } from '../models/Tile';
+import { TilePosition } from '../types';
+import { CONFIG } from '../config';
+
+describe('Tile', () => {
+  describe('constructor', () => {
+    it('should set id, type, and position properties', () => {
+      const position: TilePosition = { row: 0, col: 1 };
+      const tile = new Tile('tile-1', 0, position);
+
+      expect(tile.id).toBe('tile-1');
+      expect(tile.type).toBe(0);
+      expect(tile.position).toEqual(position);
+    });
+
+    it('should set cleared property to false by default', () => {
+      const tile = new Tile('tile-1', 0, { row: 0, col: 0 });
+      expect(tile.cleared).toBe(false);
+    });
+
+    it('should allow cleared to be set to true', () => {
+      const tile = new Tile('tile-1', 0, { row: 0, col: 0 });
+      tile.cleared = true;
+      expect(tile.cleared).toBe(true);
+    });
+  });
+
+  describe('emoji getter', () => {
+    it('should return correct emoji for type 0', () => {
+      const tile = new Tile('tile-1', 0, { row: 0, col: 0 });
+      expect(tile.emoji).toBe(CONFIG.emojis[0]);
+    });
+
+    it('should return correct emoji for type 7', () => {
+      const tile = new Tile('tile-1', 7, { row: 0, col: 0 });
+      expect(tile.emoji).toBe(CONFIG.emojis[7]);
+    });
+
+    it('should return correct emoji for type 15 (last)', () => {
+      const tile = new Tile('tile-1', 15, { row: 0, col: 0 });
+      expect(tile.emoji).toBe(CONFIG.emojis[15]);
+    });
+
+    it('should return all 16 emojis correctly', () => {
+      for (let i = 0; i < 16; i++) {
+        const tile = new Tile(`tile-${i}`, i, { row: 0, col: 0 });
+        expect(tile.emoji).toBe(CONFIG.emojis[i]);
+      }
+    });
+  });
+
+  describe('isAdjacent()', () => {
+    it('should return true for tiles adjacent horizontally', () => {
+      const tile1 = new Tile('tile-1', 0, { row: 0, col: 0 });
+      const tile2 = new Tile('tile-2', 0, { row: 0, col: 1 });
+      expect(tile1.isAdjacent(tile2)).toBe(true);
+      expect(tile2.isAdjacent(tile1)).toBe(true);
+    });
+
+    it('should return true for tiles adjacent vertically', () => {
+      const tile1 = new Tile('tile-1', 0, { row: 0, col: 0 });
+      const tile2 = new Tile('tile-2', 0, { row: 1, col: 0 });
+      expect(tile1.isAdjacent(tile2)).toBe(true);
+      expect(tile2.isAdjacent(tile1)).toBe(true);
+    });
+
+    it('should return false for diagonal tiles', () => {
+      const tile1 = new Tile('tile-1', 0, { row: 0, col: 0 });
+      const tile2 = new Tile('tile-2', 0, { row: 1, col: 1 });
+      expect(tile1.isAdjacent(tile2)).toBe(false);
+      expect(tile2.isAdjacent(tile1)).toBe(false);
+    });
+
+    it('should return false for tiles with gap of 2', () => {
+      const tile1 = new Tile('tile-1', 0, { row: 0, col: 0 });
+      const tile2 = new Tile('tile-2', 0, { row: 0, col: 2 });
+      expect(tile1.isAdjacent(tile2)).toBe(false);
+    });
+
+    it('should return false for the same tile', () => {
+      const tile = new Tile('tile-1', 0, { row: 0, col: 0 });
+      expect(tile.isAdjacent(tile)).toBe(false);
+    });
+
+    it('should return false for tiles far apart', () => {
+      const tile1 = new Tile('tile-1', 0, { row: 0, col: 0 });
+      const tile2 = new Tile('tile-2', 0, { row: 5, col: 3 });
+      expect(tile1.isAdjacent(tile2)).toBe(false);
+    });
+
+    it('should handle edge positions correctly', () => {
+      // Bottom right corner
+      const cornerTile = new Tile('tile-1', 0, { row: 9, col: 15 });
+      const adjacentLeft = new Tile('tile-2', 0, { row: 9, col: 14 });
+      const adjacentTop = new Tile('tile-3', 0, { row: 8, col: 15 });
+
+      expect(cornerTile.isAdjacent(adjacentLeft)).toBe(true);
+      expect(cornerTile.isAdjacent(adjacentTop)).toBe(true);
+    });
+  });
+
+  describe('readonly properties', () => {
+    it('should have readonly id', () => {
+      const tile = new Tile('tile-1', 0, { row: 0, col: 0 });
+      // TypeScript enforces readonly at compile time
+      // This test confirms the property exists and has correct value
+      expect(tile.id).toBe('tile-1');
+    });
+
+    it('should have readonly type', () => {
+      const tile = new Tile('tile-1', 5, { row: 0, col: 0 });
+      expect(tile.type).toBe(5);
+    });
+
+    it('should have readonly position', () => {
+      const tile = new Tile('tile-1', 0, { row: 3, col: 7 });
+      expect(tile.position.row).toBe(3);
+      expect(tile.position.col).toBe(7);
+    });
+  });
+});