Prototype neutral Semuta reactions on clean ordinary discards

tests/bot-semuta.test.ts

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+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { baseDeck } from '../game/cards';
+import { createGame, joinGame, newPlayer, viewGame, type GameView } from '../game/engine';
+import { DIFFICULTIES } from '../game/bot-profiles';
+import { botSemutaActions } from '../game/bot-semuta';
+import { richeseCards } from '../game/richese-cards';
+import { SEMUTA_DRUG_ID } from '../game/semuta-drug';
+
+const semuta = richeseCards().find((card) => card.id === SEMUTA_DRUG_ID)!;
+const event = 'discard:3:6:19';
+
+function offerView(): GameView {
+  const g = createGame('BOTSEMUTA', newPlayer('owner', 'Owner', 'atreides'));
+  joinGame(g, newPlayer('rival', 'Rival', 'fremen'));
+  const v = viewGame(g, 'owner');
+  v.status = 'playing';
+  v.players.find((p) => p.id === 'owner')!.hand!.push(semuta);
+  v.semutaReaction = {
+    event,
+    stage: 'offer',
+    passed: false,
+    canCommit: true,
+    blocked: null,
+    candidates: [],
+  };
+  return v;
+}
+
+function denyRivalPrivateFields(v: GameView) {
+  const rival = v.players.find((p) => p.id === 'rival')!;
+  for (const key of ['hand', 'traitors', 'faceDancers', 'spice'])
+    Object.defineProperty(rival, key, {
+      configurable: true,
+      get() { throw new Error(`Read rival private ${key}`); },
+    });
+}
+
+void test('all four difficulties commit using only their own card and the exact public event without mutating the projected view', () => {
+  for (const difficulty of DIFFICULTIES) {
+    const v = offerView();
+    v.players.find((p) => p.id === v.me)!.bot = difficulty;
+    const before = structuredClone(v);
+    denyRivalPrivateFields(v);
+    assert.deepEqual(botSemutaActions(v), [{ type: 'semutaCommit', event }]);
+    const rival = v.players.find((p) => p.id === 'rival')!;
+    for (const key of ['hand', 'traitors', 'faceDancers', 'spice'])
+      Reflect.deleteProperty(rival, key);
+    assert.deepEqual(v, before);
+  }
+});
+
+void test('offer never inspects an uncommitted candidate or rival custody; unable or blocked seats pass once', () => {
+  const v = offerView();
+  const reaction = v.semutaReaction!;
+  Object.defineProperty(reaction, 'candidates', {
+    get() { throw new Error('Read unrevealed fresh cards'); },
+  });
+  denyRivalPrivateFields(v);
+  assert.deepEqual(botSemutaActions(v), [{ type: 'semutaCommit', event }]);
+  v.players.find((p) => p.id === v.me)!.hand!.length = 0;
+  assert.deepEqual(botSemutaActions(v), [{ type: 'semutaPass', event }]);
+  v.players.find((p) => p.id === v.me)!.hand!.push(semuta);
+  reaction.blocked = 'No free hand slot';
+  assert.deepEqual(botSemutaActions(v), [{ type: 'semutaPass', event }]);
+  reaction.blocked = null;
+  reaction.canCommit = false;
+  assert.deepEqual(botSemutaActions(v), [{ type: 'semutaPass', event }]);
+  reaction.passed = true;
+  assert.deepEqual(botSemutaActions(v), []);
+  v.semutaReaction = null;
+  assert.deepEqual(botSemutaActions(v), []);
+});
+
+void test('all four difficulties select an exact projected candidate after commitment, never a guessed discard', () => {
+  const [first, second] = baseDeck();
+  for (const difficulty of DIFFICULTIES) {
+    const v = offerView();
+    v.players.find((p) => p.id === v.me)!.bot = difficulty;
+    v.semutaReaction = {
+      event,
+      stage: 'select',
+      passed: false,
+      canCommit: false,
+      blocked: null,
+      candidates: [first, second],
+    };
+    const before = structuredClone(v);
+    denyRivalPrivateFields(v);
+    assert.deepEqual(botSemutaActions(v), [
+      { type: 'semutaSelect', event, card: first.id },
+    ]);
+    const rival = v.players.find((p) => p.id === 'rival')!;
+    for (const key of ['hand', 'traitors', 'faceDancers', 'spice'])
+      Reflect.deleteProperty(rival, key);
+    assert.deepEqual(v, before);
+    v.semutaReaction.candidates = [second];
+    assert.deepEqual(botSemutaActions(v), [
+      { type: 'semutaSelect', event, card: second.id },
+    ]);
+    v.semutaReaction.candidates = [];
+    assert.deepEqual(botSemutaActions(v), []); // Nonclaimants receive no faces.
+  }
+});