metatrondelivery/tests/unit/geo.test.ts

import { describe, expect, it } from "vitest";
import {
  haversineDistanceKm,
  isPostalCodeListed,
  isWithinRadiusKm,
  normalizePostalCode,
  sortByDistance,
} from "../../app/lib/geo";

// Known reference distances (verifiable against any mapping service):
const TORONTO = { lat: 43.6532, lng: -79.3832 };
const OTTAWA = { lat: 45.4215, lng: -75.6972 };
const KITCHENER = { lat: 43.4516, lng: -80.4925 };

describe("haversineDistanceKm", () => {
  it("is zero for the same point", () => {
    expect(haversineDistanceKm(TORONTO, TORONTO)).toBeCloseTo(0, 5);
  });

  it("is symmetric", () => {
    expect(haversineDistanceKm(TORONTO, OTTAWA)).toBeCloseTo(haversineDistanceKm(OTTAWA, TORONTO), 8);
  });

  it("matches the known Toronto-Ottawa distance within a reasonable tolerance", () => {
    // Real-world straight-line distance is ~352 km.
    expect(haversineDistanceKm(TORONTO, OTTAWA)).toBeGreaterThan(340);
    expect(haversineDistanceKm(TORONTO, OTTAWA)).toBeLessThan(365);
  });

  it("Kitchener is closer to Toronto than Ottawa is", () => {
    expect(haversineDistanceKm(TORONTO, KITCHENER)).toBeLessThan(haversineDistanceKm(TORONTO, OTTAWA));
  });
});

describe("isWithinRadiusKm", () => {
  it("is true when distance is under the radius", () => {
    expect(isWithinRadiusKm(TORONTO, KITCHENER, 200)).toBe(true);
  });

  it("is false when distance exceeds the radius", () => {
    expect(isWithinRadiusKm(TORONTO, OTTAWA, 100)).toBe(false);
  });

  it("is true exactly at the boundary", () => {
    const d = haversineDistanceKm(TORONTO, OTTAWA);
    expect(isWithinRadiusKm(TORONTO, OTTAWA, d)).toBe(true);
  });
});

describe("normalizePostalCode / isPostalCodeListed", () => {
  it("normalizes case and whitespace", () => {
    expect(normalizePostalCode("v6b 1a1")).toBe("V6B1A1");
    expect(normalizePostalCode(" M5V 3A8 ")).toBe("M5V3A8");
  });

  it("matches regardless of formatting differences", () => {
    expect(isPostalCodeListed("m5v3a8", ["M5V 3A8", "N2G 1A1"])).toBe(true);
  });

  it("does not match a postal code outside the list", () => {
    expect(isPostalCodeListed("K1A 0A6", ["M5V 3A8", "N2G 1A1"])).toBe(false);
  });
});

describe("sortByDistance", () => {
  it("orders items nearest-first", () => {
    const items = [
      { name: "Ottawa", coordinates: OTTAWA },
      { name: "Kitchener", coordinates: KITCHENER },
    ];
    expect(sortByDistance(TORONTO, items).map((i) => i.name)).toEqual(["Kitchener", "Ottawa"]);
  });

  it("does not mutate the input array", () => {
    const items = [
      { name: "Ottawa", coordinates: OTTAWA },
      { name: "Kitchener", coordinates: KITCHENER },
    ];
    const original = [...items];
    sortByDistance(TORONTO, items);
    expect(items).toEqual(original);
  });
});