fix: ensure macOS mpv window helper is built and bundled correctly (#93)

scripts/prepare-build-assets.test.ts

@@ -0,0 +1,20 @@
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import test from 'node:test';
+
+const source = readFileSync('scripts/prepare-build-assets.mjs', 'utf8');
+
+test('macOS helper build creates dist scripts directory before swiftc output', () => {
+  const buildFunctionIndex = source.indexOf('function buildMacosHelper()');
+  assert.notEqual(buildFunctionIndex, -1);
+
+  const swiftcIndex = source.indexOf("execFileSync('swiftc'", buildFunctionIndex);
+  assert.notEqual(swiftcIndex, -1);
+
+  const ensureDirIndex = source.lastIndexOf('ensureDir(scriptsOutputDir)', swiftcIndex);
+
+  assert.ok(
+    ensureDirIndex > buildFunctionIndex,
+    'buildMacosHelper must create dist/scripts before swiftc writes the helper binary',
+  );
+});