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feat: use real BIDV bid/ask rates for forex conversion

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Replace hardcoded 0.5% spread with live buy/sell rates from BIDV bank
API. Buying USD uses bank's sell rate (higher), selling USD uses bank's
buy rate (lower). Reply shows both rates and actual spread percentage.
This commit is contained in:
tiennm99
2026-04-14 16:53:07 +07:00
parent f3aaf16d6a
commit 86268341d1
5 changed files with 65 additions and 43 deletions
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27
tests/modules/trading/handlers.test.js
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@@ -44,10 +44,16 @@ function stubFetch() {
json: () => Promise.resolve({ data: [{ close: prices[ticker] || 25 }] }),
});
}
if (url.includes("er-api")) {
if (url.includes("bidv")) {
return Promise.resolve({
ok: true,
json: () => Promise.resolve({ rates: { VND: 25400 } }),
json: () =>
Promise.resolve({
data: [
{ currency: "USD", muaCk: "25,200", ban: "25,600" },
{ currency: "EUR", muaCk: "28,000", ban: "28,500" },
],
}),
});
}
return Promise.reject(new Error(`unexpected fetch: ${url}`));
@@ -157,7 +163,7 @@ describe("trading/handlers", () => {
});
describe("handleConvert", () => {
it("converts USD to VND at bid rate (less than mid)", async () => {
it("converts USD to VND at buy rate (bank buys USD at lower price)", async () => {
const { emptyPortfolio, getPortfolio } = await import(
"../../../src/modules/trading/portfolio.js"
);
@@ -168,14 +174,14 @@ describe("trading/handlers", () => {
const ctx = makeCtx("50 USD VND");
await handleConvert(ctx, db);
expect(ctx.replies[0]).toContain("Converted");
// bid rate = 25400 * 0.995 = 25273 VND/USD → 50 * 25273 = 1,263,650
// buy rate = 25,200 → 50 * 25200 = 1,260,000 VND
const loaded = await getPortfolio(db, 42);
expect(loaded.currency.VND).toBeLessThan(50 * 25400); // less than mid rate
expect(loaded.currency.VND).toBeGreaterThan(0);
expect(ctx.replies[0]).toContain("spread");
expect(loaded.currency.VND).toBe(50 * 25200);
expect(ctx.replies[0]).toContain("buy:");
expect(ctx.replies[0]).toContain("sell:");
});
it("converts VND to USD at ask rate (costs more VND)", async () => {
it("converts VND to USD at sell rate (bank sells USD at higher price)", async () => {
const { emptyPortfolio, getPortfolio } = await import(
"../../../src/modules/trading/portfolio.js"
);
@@ -186,10 +192,9 @@ describe("trading/handlers", () => {
const ctx = makeCtx("1000000 VND USD");
await handleConvert(ctx, db);
expect(ctx.replies[0]).toContain("Converted");
// ask rate = 25400 * 1.005 = 25527 VND/USD → 1M / 25527 ≈ 39.17 USD
// sell rate = 25,600 → 1M / 25600 ≈ 39.0625 USD
const loaded = await getPortfolio(db, 42);
expect(loaded.currency.USD).toBeLessThan(1000000 / 25400); // less USD than mid
expect(loaded.currency.USD).toBeGreaterThan(0);
expect(loaded.currency.USD).toBeCloseTo(1000000 / 25600, 2);
});
it("rejects same currency conversion", async () => {