import { expect, test } from "bun:test";
import { formatRate } from "./pairs";

test("inverse yen rates retain meaningful precision instead of rounding a material FX move away", () => {
  expect(formatRate(1 / 149, "USD")).toBe("0.0067114");
  expect(formatRate(1 / 151, "USD")).toBe("0.0066225");
  expect(formatRate(149.25, "JPY")).toBe("149.25");
  expect(formatRate(1.08, "USD")).toBe("1.0800");
  expect(formatRate(Number.POSITIVE_INFINITY, "USD")).toBe("—");
  expect(formatRate(0, "USD")).toBe("—");
});

test("a cross ticking across a power of ten keeps the decimals of its reference rate", () => {
  expect(formatRate(0.00999, "AUD", 0.01001)).toBe("0.009990");
  expect(formatRate(0.01001, "AUD", 0.00999)).toBe("0.0100100");
});