1 files changed, 24 insertions, 0 deletions
diff --git a/viewer/tests/atmosphere.test.mjs b/viewer/tests/atmosphere.test.mjs
new file mode 100644
index 0000000..79f183a
--- /dev/null
+++ b/viewer/tests/atmosphere.test.mjs
@@ -0,0 +1,24 @@
+import './_planet.mjs';
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import './importmap.mjs';
+
+const { atmosphere, SKY_FULL_KM, SKY_NONE_KM } = await import('../js/atmosphere.js');
+const lum = c => c[0] + c[1] + c[2];
+
+test('full sky near the ground, none in space, a smooth fade between', () => {
+  assert.equal(atmosphere(5).amount, 1);
+  assert.equal(atmosphere(SKY_FULL_KM).amount, 1);
+  assert.equal(atmosphere(SKY_NONE_KM).amount, 0);
+  assert.equal(atmosphere(5000).amount, 0);
+  const m = atmosphere(60).amount;
+  assert.ok(m > 0.2 && m < 0.8);
+});
+
+test('day sky is blue, lighter at the horizon; night is dark; Sky off = day', () => {
+  const d = atmosphere(1, null);
+  assert.ok(d.zenith[2] > d.zenith[0] && lum(d.horizon) > lum(d.zenith));
+  const n = atmosphere(1, -1);
+  assert.ok(lum(n.horizon) < 0.3 * lum(d.horizon));
+  assert.deepEqual(atmosphere(1, 1), d);
+});