fool-cardgame/tests/core/bot/BasicBot.spec.ts

import { describe, expect, it } from 'vitest';
import { ActionType } from '@core/rules/Action';
import { Phase } from '@core/rules/GameState';
import { projectView } from '@core/bot/PlayerView';
import { BasicBot } from '@core/bot/BasicBot';
import { makeState } from '../../support/fixtures';

const YOU = 'you';
const BOT = 'bot';

const bot = new BasicBot();

function decideFor(state: Parameters<typeof projectView>[0], player: string) {
    return bot.decide(projectView(state, player));
}

describe('BasicBot opening a turn', () => {
    it('leads with its cheapest non-trump', () => {
        const state = makeState({
            hands: { [BOT]: '9C 6D KH 7S', [YOU]: 'AH AD' },
            trump: 'S',
            deck: '10C 10D',
            attacker: BOT,
        });

        const action = decideFor(state, BOT);
        expect(action.type).toBe(ActionType.Attack);
        expect(action).toMatchObject({ card: expect.objectContaining({ code: '6♦' }) });
    });

    it('keeps its trumps back even when they are cheaper', () => {
        const state = makeState({
            hands: { [BOT]: '6S 9C', [YOU]: 'AH AD' },
            trump: 'S',
            deck: '10C 10D',
            attacker: BOT,
        });

        expect(decideFor(state, BOT)).toMatchObject({
            card: expect.objectContaining({ code: '9♣' }),
        });
    });

    it('leads with its cheapest trump when that is all it holds', () => {
        const state = makeState({
            hands: { [BOT]: 'KS 7S', [YOU]: 'AH AD' },
            trump: 'S',
            deck: '10C 10D',
            attacker: BOT,
        });

        expect(decideFor(state, BOT)).toMatchObject({
            card: expect.objectContaining({ code: '7♠' }),
        });
    });
});

describe('BasicBot defending', () => {
    it('beats with the cheapest card that works', () => {
        const state = makeState({
            hands: { [YOU]: 'AC', [BOT]: '10D 8D QD 6S' },
            trump: 'S',
            deck: '10C 10H',
            attacker: YOU,
            table: [{ attack: '7D' }],
            phase: Phase.Defence,
        });

        expect(decideFor(state, BOT)).toMatchObject({
            type: ActionType.Defend,
            card: expect.objectContaining({ code: '8♦' }),
        });
    });

    it('prefers any non-trump over a cheap trump', () => {
        const state = makeState({
            hands: { [YOU]: 'AC', [BOT]: 'AD 6S' },
            trump: 'S',
            deck: '10C 10H',
            attacker: YOU,
            table: [{ attack: '7D' }],
            phase: Phase.Defence,
        });

        expect(decideFor(state, BOT)).toMatchObject({
            card: expect.objectContaining({ code: 'A♦' }),
        });
    });

    it('spends a trump when nothing else beats the attack', () => {
        const state = makeState({
            hands: { [YOU]: 'AC', [BOT]: '6D KS 7S' },
            trump: 'S',
            deck: '10C 10H',
            attacker: YOU,
            table: [{ attack: '7D' }],
            phase: Phase.Defence,
        });

        expect(decideFor(state, BOT)).toMatchObject({
            card: expect.objectContaining({ code: '7♠' }),
        });
    });

    it('takes when it cannot beat the attack', () => {
        const state = makeState({
            hands: { [YOU]: 'AC', [BOT]: '6D 6H' },
            trump: 'S',
            deck: '10C 10H',
            attacker: YOU,
            table: [{ attack: '7D' }],
            phase: Phase.Defence,
        });

        expect(decideFor(state, BOT).type).toBe(ActionType.Take);
    });
});

describe('BasicBot adding to an attack', () => {
    it('throws in every eligible non-trump, cheapest first', () => {
        const state = makeState({
            hands: { [BOT]: '7H 7C KD', [YOU]: 'AH AD AC' },
            trump: 'S',
            deck: '10C 10D',
            attacker: BOT,
            table: [{ attack: '7D', defence: '9D' }],
            phase: Phase.Reinforce,
        });

        expect(decideFor(state, BOT)).toMatchObject({
            type: ActionType.Attack,
            card: expect.objectContaining({ code: '7♣' }),
        });
    });

    it('holds its trumps back while the deck still has cards', () => {
        const state = makeState({
            hands: { [BOT]: '7S KD', [YOU]: 'AH AD AC' },
            trump: 'S',
            deck: '10C 10D',
            attacker: BOT,
            table: [{ attack: '7D', defence: '9D' }],
            phase: Phase.Reinforce,
        });

        expect(decideFor(state, BOT).type).toBe(ActionType.Pass);
    });

    it('holds its trumps back at the end if it still has other cards', () => {
        const state = makeState({
            hands: { [BOT]: '7S KD', [YOU]: 'AH AD AC' },
            trump: 'S',
            attacker: BOT,
            table: [{ attack: '7D', defence: '9D' }],
            phase: Phase.Reinforce,
        });

        expect(state.deck).toHaveLength(0);
        expect(decideFor(state, BOT).type).toBe(ActionType.Pass);
    });

    it('throws in a trump once the deck is empty and trumps are all it has', () => {
        const state = makeState({
            hands: { [BOT]: '7S KS', [YOU]: 'AH AD AC' },
            trump: 'S',
            attacker: BOT,
            table: [{ attack: '7D', defence: '9D' }],
            phase: Phase.Reinforce,
        });

        expect(decideFor(state, BOT)).toMatchObject({
            type: ActionType.Attack,
            card: expect.objectContaining({ code: '7♠' }),
        });
    });
});

describe('BasicBot contract', () => {
    it('refuses to move out of turn', () => {
        const state = makeState({
            hands: { [YOU]: '6C', [BOT]: '8C' },
            trump: 'S',
            deck: '10C',
            attacker: YOU,
        });
        expect(() => decideFor(state, BOT)).toThrow(/out of turn/);
    });
});