feat(scan-sprite): walk dir, normalise aliases, detect collisions

tests/scan-sprite.test.js

@@ -0,0 +1,47 @@
+const { test } = require('node:test');
+const assert = require('node:assert');
+const path = require('node:path');
+const { scanSpriteSourceDir } = require('../src/scan-sprite');
+
+const FRESH = path.resolve(__dirname, 'fixtures/sprite-fresh');
+const COLLISION = path.resolve(__dirname, 'fixtures/sprite-collision');
+
+test('scan-sprite: 4 PNGs, alphabetical, no errors', () => {
+    const { sources, errors } = scanSpriteSourceDir(FRESH, {});
+    assert.deepStrictEqual(errors, []);
+    assert.strictEqual(sources.length, 4);
+    assert.strictEqual(sources[0].alias, 'barrel_large');
+    assert.strictEqual(sources[1].alias, 'bed1');
+    assert.strictEqual(sources[2].alias, 'bench1');
+    assert.strictEqual(sources[3].alias, 'sack');
+});
+
+test('scan-sprite: sources carry sourcePath + sourceFile', () => {
+    const { sources } = scanSpriteSourceDir(FRESH, {});
+    assert.ok(sources[1].sourcePath.endsWith('Bed1.png'));
+    assert.strictEqual(sources[1].sourceFile, 'Bed1.png');
+});
+
+test('scan-sprite: alias collision -> loud error', () => {
+    const { sources, errors } = scanSpriteSourceDir(COLLISION, {});
+    assert.strictEqual(sources.length, 0);
+    assert.strictEqual(errors.length, 1);
+    assert.match(errors[0], /alias collision/i);
+    assert.match(errors[0], /bed1/);
+});
+
+test('scan-sprite: missing dir -> error', () => {
+    const { sources, errors } = scanSpriteSourceDir('/nonexistent/path', {});
+    assert.strictEqual(sources.length, 0);
+    assert.ok(errors[0].includes('does not exist'));
+});
+
+test('scan-sprite: applies stripPrefix option', () => {
+    const { sources, errors } = scanSpriteSourceDir(FRESH, {
+        stripPrefix: 'Bed',
+    });
+    assert.deepStrictEqual(errors, []);
+    // Bed1 -> 1, Bench1 not stripped -> bench1, etc.
+    const aliases = sources.map(s => s.alias).sort();
+    assert.ok(aliases.includes('1'));
+});