const test = require('node:test');
const assert = require('node:assert/strict');

const gravity = require('../src/helper/gravity.js');

test('standard gravity constant is available', () => {
  assert.ok(Math.abs(gravity.getStandardGravity() - 9.80665) < 1e-9);
});

test('local gravity decreases with elevation', () => {
  const seaLevel = gravity.getLocalGravity(45, 0);
  const high = gravity.getLocalGravity(45, 1000);
  assert.ok(high < seaLevel);
});

test('pressureHead and weightForce use local gravity', () => {
  const dp = gravity.pressureHead(1000, 5, 45, 0);
  const force = gravity.weightForce(2, 45, 0);
  assert.ok(dp > 0);
  assert.ok(force > 0);
});
