1 files changed, 36 insertions, 0 deletions
diff --git a/viewer/tests/profile.test.mjs b/viewer/tests/profile.test.mjs
new file mode 100644
index 0000000..9418565
--- /dev/null
+++ b/viewer/tests/profile.test.mjs
@@ -0,0 +1,36 @@
+import './_planet.mjs';
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { profileModel, sampleAt } from '../js/profile.js';
+
+const S = [{ d_km: 0, z_m: -200, water: true }, { d_km: 50, z_m: 300, water: false }, { d_km: 100, z_m: 1200, water: false },
+  { d_km: 150, z_m: -50, water: true }];
+
+test('model spans distance and elevation incl. sea level', () => {
+  const m = profileModel(S, 320, 130);
+  assert.ok(m.line.startsWith('M'));
+  assert.equal(m.L, 150);
+  assert.ok(m.lo <= -200 && m.hi >= 1200);
+  assert.ok(m.Y(0) > m.Y(1200) && m.Y(0) < m.Y(-200));
+  assert.ok(Math.abs(m.xAt(m.X(75)) - 75) < 1e-9);
+  assert.equal(m.seaY, m.Y(0));
+});
+
+test('water runs cover the water samples, half a step either side', () => {
+  const m = profileModel(S, 320, 130);
+  assert.equal(m.water.length, 2);
+  assert.ok(Math.abs(m.water[0][0] - m.X(0)) < 1e-9 && Math.abs(m.water[0][1] - m.X(25)) < 1e-9);
+  assert.ok(Math.abs(m.water[1][0] - m.X(125)) < 1e-9 && Math.abs(m.water[1][1] - m.X(150)) < 1e-9);
+});
+
+test('flat land still gets a usable vertical range', () => {
+  const m = profileModel([{ d_km: 0, z_m: 10, water: false }, { d_km: 5, z_m: 10, water: false }], 320, 130);
+  assert.ok(m.hi - m.lo >= 100);
+});
+
+test('nearest sample by distance', () => {
+  assert.equal(sampleAt(S, -5), 0);
+  assert.equal(sampleAt(S, 74), 1);
+  assert.equal(sampleAt(S, 76), 2);
+  assert.equal(sampleAt(S, 999), 3);
+});