import { describe, expect, it } from 'vitest';
import { haversineKm } from './geo';

describe('haversineKm', () => {
  it('returns 0 for identical points', () => {
    expect(haversineKm(50.03, 8.57, 50.03, 8.57)).toBeCloseTo(0, 10);
  });

  it('computes the London → Paris great-circle distance (~343 km)', () => {
    const km = haversineKm(51.47, -0.454, 49.0097, 2.5479); // LHR → CDG
    expect(km).toBeGreaterThan(330);
    expect(km).toBeLessThan(360);
  });

  it('is symmetric', () => {
    const a = haversineKm(50.03, 8.57, 40.47, -3.56); // FRA → MAD
    const b = haversineKm(40.47, -3.56, 50.03, 8.57);
    expect(a).toBeCloseTo(b, 10);
  });
});