hope-events/backend/tests/coupons.test.js

const {
  normalizeCode,
  buildCouponLines,
  computeCouponDiscount,
  validateCoupon,
  describeCoupon,
} = require('../src/utils/coupons');
const { computeRegistrationTotalDue, staffPriceFor } = require('../src/utils/pricing');

const NOW = new Date('2026-06-15T10:00:00Z');
const PAST = new Date('2026-06-01T00:00:00Z');
const FUTURE = new Date('2026-07-01T00:00:00Z');

const coupon = (over = {}) => ({
  id: 'c1', code: 'STAFF50', type: 'percent', value: 50, stackEarlyBird: false, active: true,
  validFrom: null, validUntil: null, maxUses: null, maxUsesPerUser: 1, minQuantity: null,
  restrictRoles: [], restrictDomain: null, events: [], options: [], allowedUsers: [],
  ...over,
});

// 2 adult tickets at R200 (standard) and 1 T-shirt at R100.
const LINES = [
  { eventOptionId: 'adult', variantId: null, quantity: 2, unitPrice: 200, basePrice: 200 },
  { eventOptionId: 'shirt', variantId: 'L', quantity: 1, unitPrice: 100, basePrice: 100 },
];

describe('normalizeCode', () => {
  test('trims and uppercases', () => {
    expect(normalizeCode('  staff50 ')).toBe('STAFF50');
    expect(normalizeCode(null)).toBe('');
  });
});

describe('computeCouponDiscount', () => {
  test('percentage over the whole event', () => {
    expect(computeCouponDiscount(coupon(), LINES)).toBe(250);
  });

  test('fixed amount, capped at what is in scope', () => {
    expect(computeCouponDiscount(coupon({ type: 'fixed', value: 120 }), LINES)).toBe(120);
    expect(computeCouponDiscount(coupon({ type: 'fixed', value: 9999 }), LINES)).toBe(500);
  });

  test('comp covers only in-scope options', () => {
    const c = coupon({ type: 'comp', options: [{ eventOptionId: 'adult', variantId: null }] });
    expect(computeCouponDiscount(c, LINES)).toBe(400);
  });

  test('scope can target a single variant', () => {
    const c = coupon({ type: 'comp', options: [{ eventOptionId: 'shirt', variantId: 'M' }] });
    expect(computeCouponDiscount(c, LINES)).toBe(0);
    const c2 = coupon({ type: 'comp', options: [{ eventOptionId: 'shirt', variantId: 'L' }] });
    expect(computeCouponDiscount(c2, LINES)).toBe(100);
  });

  test('best price wins against early-bird when not stacking', () => {
    // Early-bird R150 vs standard R200: 10% off standard = R180, early-bird already beats it.
    const eb = [{ eventOptionId: 'adult', variantId: null, quantity: 1, unitPrice: 150, basePrice: 200 }];
    expect(computeCouponDiscount(coupon({ value: 10 }), eb)).toBe(0);
    // 50% off standard = R100, beats R150 early-bird by R50.
    expect(computeCouponDiscount(coupon({ value: 50 }), eb)).toBe(50);
    // Fixed R80 off standard = R120, beats R150 by R30.
    expect(computeCouponDiscount(coupon({ type: 'fixed', value: 80 }), eb)).toBe(30);
  });

  test('stacking applies on top of the early-bird price', () => {
    const eb = [{ eventOptionId: 'adult', variantId: null, quantity: 1, unitPrice: 150, basePrice: 200 }];
    expect(computeCouponDiscount(coupon({ value: 10, stackEarlyBird: true }), eb)).toBe(15);
    expect(computeCouponDiscount(coupon({ type: 'fixed', value: 80, stackEarlyBird: true }), eb)).toBe(80);
  });

  test('never goes below zero or above the price', () => {
    expect(computeCouponDiscount(coupon({ value: 150 }), LINES)).toBe(500);
    expect(computeCouponDiscount(coupon({ type: 'fixed', value: -10 }), LINES)).toBe(0);
    expect(computeCouponDiscount(coupon(), [])).toBe(0);
  });
});

describe('validateCoupon', () => {
  const ctx = (over = {}) => ({ eventId: 'e1', user: { id: 'u1', role: 'user', email: 'a@church.org' }, now: NOW, usesTotal: 0, usesByUser: 0, lines: LINES, ...over });

  test('accepts an unrestricted active code', () => {
    expect(validateCoupon(coupon(), ctx())).toEqual({ ok: true });
  });

  test('rejects inactive, not-yet-valid and expired codes', () => {
    expect(validateCoupon(coupon({ active: false }), ctx()).ok).toBe(false);
    expect(validateCoupon(coupon({ validFrom: FUTURE }), ctx()).message).toMatch(/isn't valid yet/);
    expect(validateCoupon(coupon({ validUntil: PAST }), ctx()).message).toMatch(/expired/);
  });

  test('limits to the coupon events when any are set', () => {
    expect(validateCoupon(coupon({ events: [{ eventId: 'e2' }] }), ctx()).ok).toBe(false);
    expect(validateCoupon(coupon({ events: [{ eventId: 'e1' }, { eventId: 'e2' }] }), ctx()).ok).toBe(true);
  });

  test('restricted codes need a known account matching any restriction', () => {
    const staffOnly = coupon({ restrictRoles: ['staff', 'supervisor', 'admin'] });
    expect(validateCoupon(staffOnly, ctx({ user: null })).message).toMatch(/Log in/);
    expect(validateCoupon(staffOnly, ctx()).ok).toBe(false);
    expect(validateCoupon(staffOnly, ctx({ user: { id: 'u1', role: 'staff', email: 'x@y.z' } })).ok).toBe(true);
    expect(validateCoupon(coupon({ restrictDomain: '@church.org' }), ctx()).ok).toBe(true);
    expect(validateCoupon(coupon({ restrictDomain: 'other.org' }), ctx()).ok).toBe(false);
    expect(validateCoupon(coupon({ allowedUsers: [{ userId: 'u1' }] }), ctx()).ok).toBe(true);
  });

  test('enforces total and per-user use limits', () => {
    expect(validateCoupon(coupon({ maxUses: 5 }), ctx({ usesTotal: 5 })).message).toMatch(/fully used/);
    expect(validateCoupon(coupon({ maxUsesPerUser: 1 }), ctx({ usesByUser: 1 })).message).toMatch(/already used/);
    expect(validateCoupon(coupon({ maxUsesPerUser: null }), ctx({ usesByUser: 9 })).ok).toBe(true);
  });

  test('needs qualifying items and the minimum quantity', () => {
    expect(validateCoupon(coupon({ options: [{ eventOptionId: 'other' }] }), ctx()).message).toMatch(/doesn't apply/);
    expect(validateCoupon(coupon({ minQuantity: 4 }), ctx()).message).toMatch(/at least 4/);
    expect(validateCoupon(coupon({ minQuantity: 3 }), ctx()).ok).toBe(true);
  });
});

describe('buildCouponLines', () => {
  test('one line per tranche; early-bird tranches keep the standard price as base', () => {
    const reg = {
      registrationOptions: [{
        eventOptionId: 'adult', variantId: null, quantity: 3,
        eventOption: { price: 200, variants: [] },
        tranches: [
          { quantity: 2, priceSnapshot: 150, appliedTierId: 'tier1' },
          { quantity: 1, priceSnapshot: 200, appliedTierId: null },
        ],
      }],
    };
    expect(buildCouponLines(reg)).toEqual([
      { eventOptionId: 'adult', variantId: null, quantity: 2, unitPrice: 150, basePrice: 200 },
      { eventOptionId: 'adult', variantId: null, quantity: 1, unitPrice: 200, basePrice: 200 },
    ]);
  });
});

describe('computeRegistrationTotalDue with a discount', () => {
  const reg = (discountTotal) => ({
    discountTotal,
    registrationOptions: [{ quantity: 2, tranches: [{ quantity: 2, priceSnapshot: 100 }] }],
  });

  test('subtracts the coupon discount', () => {
    expect(computeRegistrationTotalDue(reg(50), NOW)).toBe(150);
  });

  test('never goes below zero', () => {
    expect(computeRegistrationTotalDue(reg(500), NOW)).toBe(0);
  });
});

describe('staffPriceFor', () => {
  const option = { price: 200, staffPrice: 50, variants: [{ id: 'v1', staffPrice: 20 }, { id: 'v2', staffPrice: null }] };

  test('applies to Staff and above only', () => {
    expect(staffPriceFor(option, null, { role: 'staff' })).toBe(50);
    expect(staffPriceFor(option, null, { role: 'admin' })).toBe(50);
    expect(staffPriceFor(option, null, { role: 'user' })).toBeNull();
    expect(staffPriceFor(option, null, null)).toBeNull();
  });

  test('a variant staff price overrides the option one', () => {
    expect(staffPriceFor(option, 'v1', { role: 'staff' })).toBe(20);
    expect(staffPriceFor(option, 'v2', { role: 'staff' })).toBe(50);
  });
});

describe('describeCoupon', () => {
  test('summarises each type', () => {
    expect(describeCoupon(coupon())).toBe('50% off');
    expect(describeCoupon(coupon({ type: 'fixed', value: 25 }))).toBe('R25.00 off');
    expect(describeCoupon(coupon({ type: 'comp' }))).toBe('Free');
  });
});