step 10.18: wip (not ticked)

tests/integration/step-10.18.test.js

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+// Step 10.18: Balance pass — assert Meadows level-1 win rate within 70–90% using fixed seed.
+const { describe, it, before, after } = require('node:test');
+const assert = require('node:assert/strict');
+const { resolveCombat } = require('../../src/game/combat');
+const { calcDerived } = require('../../src/game/stats');
+const { getClass, getBaseStats } = require('../../src/game/classes');
+const { mulberry32 } = require('../../src/utils/rng');
+const { setup, teardown, cleanup } = require('../helpers');
+
+// ─── Helpers ───────────────────────────────────────────────────────────────
+
+/**
+ * Simulate one hunt: hero vs a randomly-weighted monster from a zone.
+ * Uses the same weighted-pick logic as huntService.
+ */
+function pickAndFight(zoneKey, classKey, rng) {
+  const cls = getClass(classKey);
+  const base = getBaseStats(classKey);
+  const derived = calcDerived(base, 1, classKey);
+
+  const hero = {
+    class: classKey,
+    level: 1,
+    hpCurrent: derived.maxHp,
+    str: base.str, agi: base.agi, int: base.int, vit: base.vit,
+  };
+
+  // Monster data from the DB (meadows monsters)
+  const monsters = {
+    meadows: [
+      { name: 'Giant Rat', level: 1, hp: 55, attack: 15, defense: 5, speed: 10, weight: 30 },
+      { name: 'Meadow Wolf', level: 2, hp: 85, attack: 22, defense: 9, speed: 14, weight: 20 },
+      { name: 'Goblin Scrapper', level: 3, hp: 130, attack: 28, defense: 12, speed: 10, weight: 15 },
+    ],
+  };
+
+  const zoneMonsters = monsters[zoneKey];
+  const total = zoneMonsters.reduce((s, m) => s + m.weight, 0);
+  let r = rng() * total;
+  let monster = zoneMonsters[zoneMonsters.length - 1];
+  for (const m of zoneMonsters) {
+    r -= m.weight;
+    if (r < 0) { monster = m; break; }
+  }
+
+  const fight = resolveCombat(hero, monster, rng);
+  return fight.winner === 'hero';
+}
+
+// ─── Tests ─────────────────────────────────────────────────────────────────
+
+describe('balance: Meadows level-1 win rate', () => {
+  const rounds = 200;
+  const SEED = 12345;
+
+  it('Meadows level-1 win rate is between 70% and 90% for all classes', () => {
+    let totalWins = 0;
+    let totalFights = 0;
+
+    for (let r = 0; r < rounds; r++) {
+      for (const classKey of ['warrior', 'mage', 'ranger']) {
+        const rng = mulberry32(SEED + r * 100 + ['warrior', 'mage', 'ranger'].indexOf(classKey));
+        const won = pickAndFight('meadows', classKey, rng);
+        if (won) totalWins++;
+        totalFights++;
+      }
+    }
+
+    const winRate = totalWins / totalFights;
+    assert.ok(
+      winRate >= 0.70 && winRate <= 0.90,
+      `Meadows level-1 win rate is ${(winRate * 100).toFixed(2)}% (expected 70–90%)`
+    );
+  });
+
+  it('Meadows level-1 win rate is consistent across different seeds', () => {
+    // Run with 3 different seeds and check all are in range
+    for (const seed of [42, 99, 7777]) {
+      let totalWins = 0;
+      let totalFights = 0;
+
+      for (let r = 0; r < rounds; r++) {
+        for (const classKey of ['warrior', 'mage', 'ranger']) {
+          const rng = mulberry32(seed + r * 100 + ['warrior', 'mage', 'ranger'].indexOf(classKey));
+          const won = pickAndFight('meadows', classKey, rng);
+          if (won) totalWins++;
+          totalFights++;
+        }
+      }
+
+      const winRate = totalWins / totalFights;
+      assert.ok(
+        winRate >= 0.70 && winRate <= 0.90,
+        `Seed ${seed}: Meadows level-1 win rate is ${(winRate * 100).toFixed(2)}% (expected 70–90%)`
+      );
+    }
+  });
+});
+
+describe('balance: Crags level-1 win rate', () => {
+  const rounds = 200;
+  const SEED = 12345;
+
+  it('Crags level-1 win rate is ≤ 15% for all classes', () => {
+    let totalWins = 0;
+    let totalFights = 0;
+
+    const monsters = {
+      crags: [
+        { name: 'Ember Imp', level: 10, hp: 200, attack: 44, defense: 22, speed: 18, weight: 25 },
+        { name: 'Stone Golem', level: 12, hp: 420, attack: 50, defense: 52, speed: 5, weight: 10 },
+        { name: 'Ashfang Drake', level: 14, hp: 480, attack: 62, defense: 38, speed: 16, weight: 5 },
+      ],
+    };
+
+    for (let r = 0; r < rounds; r++) {
+      for (const classKey of ['warrior', 'mage', 'ranger']) {
+        const rng = mulberry32(SEED + r * 100 + ['warrior', 'mage', 'ranger'].indexOf(classKey));
+
+        const cls = getClass(classKey);
+        const base = getBaseStats(classKey);
+        const derived = calcDerived(base, 1, classKey);
+
+        const hero = {
+          class: classKey,
+          level: 1,
+          hpCurrent: derived.maxHp,
+          str: base.str, agi: base.agi, int: base.int, vit: base.vit,
+        };
+
+        const zoneMonsters = monsters.crags;
+        const total = zoneMonsters.reduce((s, m) => s + m.weight, 0);
+        let cr = rng() * total;
+        let monster = zoneMonsters[zoneMonsters.length - 1];
+        for (const m of zoneMonsters) {
+          cr -= m.weight;
+          if (cr < 0) { monster = m; break; }
+        }
+
+        const fight = resolveCombat(hero, monster, rng);
+        if (fight.winner === 'hero') totalWins++;
+        totalFights++;
+      }
+    }
+
+    const winRate = totalWins / totalFights;
+    assert.ok(
+      winRate <= 0.15,
+      `Crags level-1 win rate is ${(winRate * 100).toFixed(2)}% (expected ≤ 15%)`
+    );
+  });
+});