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frontend/camera.test.js

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+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { Camera } from './camera.js';
+const close = (a,b) => assert.ok(Math.abs(a-b)<1e-8,`${a} != ${b}`);
+test('fit preserves sheet aspect ratio without padding',()=> {
+  const c = new Camera({x:0,y:-760,width:1150,height:760},1920,1080);
+  close(c.scale,1080/760); close(c.y,1080);
+  const center = c.world(960,540); close(center.x,575); close(center.y,-380);
+});
+test('zoom retains exact world coordinate under cursor',()=> {
+  const c = new Camera({x:0,y:-760,width:1150,height:760},1000,800);
+  const p = c.world(121,534); c.zoom(3.2,121,534); const q = c.world(121,534);
+  close(p.x,q.x); close(p.y,q.y); c.pan(12,-8); const r=c.world(133,526); close(r.x,p.x); close(r.y,p.y);
+});
+test('zoom is bounded for hostile wheel deltas',()=> {
+  const c = new Camera({x:0,y:0,width:100,height:100},1000,800);
+  c.zoom(1e30,0,0); close(c.scale,c.fitScale*200);
+  c.zoom(1e-30,0,0); close(c.scale,c.fitScale*.05);
+});