test(03-01): add failing tests for word lists per level

- Tests for wordsByLevel entries levels 1-6
- Tests for allKeys-only characters validation
- Tests for max 5 chars per word
- Tests for getWordsForLevel random selection

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/game/words.test.ts

@@ -0,0 +1,74 @@
+import { describe, it, expect } from "vitest";
+import { wordsByLevel, getWordsForLevel } from "./words";
+import { getKeysUpToLevel } from "./levels";
+
+describe("wordsByLevel", () => {
+	it("has entries for levels 1-6", () => {
+		for (let level = 1; level <= 6; level++) {
+			expect(wordsByLevel[level]).toBeDefined();
+			expect(Array.isArray(wordsByLevel[level])).toBe(true);
+		}
+	});
+
+	it("each level has at least 8 words", () => {
+		for (let level = 1; level <= 6; level++) {
+			expect(wordsByLevel[level]!.length).toBeGreaterThanOrEqual(8);
+		}
+	});
+
+	it("every word in level N uses only characters from that level's allKeys (no spaces)", () => {
+		for (let level = 1; level <= 6; level++) {
+			const allowedKeys = getKeysUpToLevel(level).filter((k) => k !== " ");
+			const words = wordsByLevel[level]!;
+			for (const word of words) {
+				for (const char of word) {
+					expect(
+						allowedKeys.includes(char),
+						`Word "${word}" in level ${level} contains "${char}" which is not in allowed keys [${allowedKeys.join(", ")}]`,
+					).toBe(true);
+				}
+			}
+		}
+	});
+
+	it("no word exceeds 5 characters", () => {
+		for (let level = 1; level <= 6; level++) {
+			const words = wordsByLevel[level]!;
+			for (const word of words) {
+				expect(
+					word.length,
+					`Word "${word}" in level ${level} has ${word.length} chars (max 5)`,
+				).toBeLessThanOrEqual(5);
+			}
+		}
+	});
+});
+
+describe("getWordsForLevel", () => {
+	it("returns the requested count of random words from that level", () => {
+		const words = getWordsForLevel(3, 5);
+		expect(words).toHaveLength(5);
+		for (const word of words) {
+			expect(wordsByLevel[3]).toContain(word);
+		}
+	});
+
+	it("returns empty array for non-existent level", () => {
+		expect(getWordsForLevel(99, 5)).toEqual([]);
+		expect(getWordsForLevel(0, 5)).toEqual([]);
+	});
+
+	it("can return more words than list length (with replacement)", () => {
+		const words = getWordsForLevel(1, 20);
+		expect(words).toHaveLength(20);
+		for (const word of words) {
+			expect(wordsByLevel[1]).toContain(word);
+		}
+	});
+
+	it("returns unique words when count <= list length (without replacement)", () => {
+		const words = getWordsForLevel(3, 5);
+		const unique = new Set(words);
+		expect(unique.size).toBe(5);
+	});
+});