agent updates

test/gravity.test.js

@@ -0,0 +1,21 @@
+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);
+});