edr-platform/apps/edr-passenger-api/test/pricing-currency.e2e-spec.ts

/**
 * Currency / FX suite (matrix Suite C). Exercises CurrencyService directly.
 *   C2 🔴 missing rate: getExchangeRate() silently returns 1.0 while getRateOrThrow() throws —
 *         the display path degrades but the charge path errors on the SAME condition (divergence).
 *   C3 🔴 a future-dated rate is applied immediately (no `effectiveDate <= now` filter).
 *   C5 🔴 conversion routines disagree on units: displayMinorToChargeMajor / convertMinorToChargeMajor
 *         return MAJOR units, convertEtbMinorToChargeMinor returns MINOR — a 100x unit landmine both
 *         written into fields named `amountMinor` at their call sites.
 */
import { CurrencyService } from "../src/modules/currency/currency.service";
import { createServiceHarness, ServiceHarness } from "./setup/slim-app";
import { resetAndSeedCore, USD_TO_ETB } from "./fixtures/seed-core";

describe("Pricing — CurrencyService (Suite C)", () => {
  let harness: ServiceHarness;
  let currency: CurrencyService;

  beforeAll(async () => {
    harness = await createServiceHarness();
    currency = harness.moduleRef.get(CurrencyService);
  });
  afterAll(async () => {
    await harness?.close();
  });
  beforeEach(async () => {
    await resetAndSeedCore(harness.prisma);
  });

  it("C2 🔴 same DB state, 100x divergence: getExchangeRate → 1.0, getRateOrThrow → 100 (via inverse)", async () => {
    // Remove only the DIRECT USD→ETB row; the inverse ETB→USD (0.01) from the fixture stays.
    await harness.prisma.currencyExchangeRate.deleteMany({
      where: { fromCurrency: "USD", toCurrency: "ETB" },
    });

    // Display/fare path (getExchangeRate) has NO inverse fallback → silently returns 1.0 (wrong).
    await expect(currency.getExchangeRate("USD" as any, "ETB" as any)).resolves.toBe(1.0);

    // Charge path (getRateOrThrow) DOES fall back to the inverse → 1 / 0.01 = 100 (correct).
    await expect(
      currency.getRateOrThrow("USD" as any, "ETB" as any),
    ).resolves.toBe(USD_TO_ETB);
    // → the display fare and the charged amount for the same trip differ by 100x.
  });

  it("C2b 🔴 truly-missing pair: getExchangeRate → 1.0 (silent), getRateOrThrow → throws", async () => {
    await harness.prisma.currencyExchangeRate.deleteMany({
      where: {
        OR: [
          { fromCurrency: "USD", toCurrency: "ETB" },
          { fromCurrency: "ETB", toCurrency: "USD" },
        ],
      },
    });
    await expect(currency.getExchangeRate("USD" as any, "ETB" as any)).resolves.toBe(1.0);
    await expect(
      currency.getRateOrThrow("USD" as any, "ETB" as any),
    ).rejects.toThrow(/No exchange rate/i);
  });

  it("C3 🔴 a future-dated rate is used right now (no effective-date gate)", async () => {
    const future = new Date(Date.now() + 365 * 24 * 3600 * 1000);
    await harness.prisma.currencyExchangeRate.create({
      data: { fromCurrency: "ETB", toCurrency: "USD", rate: 999, effectiveDate: future },
    });

    // Correct behavior: ignore not-yet-effective rates. Actual: latest-by-date wins immediately.
    const rate = await currency.getExchangeRate("ETB" as any, "USD" as any);
    expect(rate).toBe(999);
  });

  it("C5 🔴 conversion routines return different UNITS for the same money (100x apart)", async () => {
    // 100000 ETB minor = 1000.00 ETB. With ETB→USD = 1/100:
    const asMajor = await currency.convertMinorToChargeMajor(100000, "ETB", "USD"); // → 10.00 (major)
    const asMinor = await currency.convertEtbMinorToChargeMinor(100000, "USD"); // → 1000 (minor)

    expect(asMajor).toBeCloseTo(1000 / USD_TO_ETB, 2); // 10.00
    expect(asMinor).toBe(Math.round((100000 * 1) / USD_TO_ETB)); // 1000
    // Same amount, but the two results differ by 100x — and both feed fields named `amountMinor`.
    expect(asMinor).toBe(asMajor * 100);
  });
});