fix: harden empty asset materialization

tests/integration/materialize-empty-asset-set.test.mjs

@@ -0,0 +1,58 @@
+import { lstat, mkdir, mkdtemp, rm, symlink, writeFile } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { afterEach, describe, expect, it } from 'vitest';
+import {
+  assertPreparedAssetDirectoryIdentity,
+  materializeEmptyAssetSet,
+} from '../../scripts/materialize-empty-asset-set.mjs';
+
+const temporaryRoots = [];
+
+const createScratchRepository = async () => {
+  const root = await mkdtemp(join(tmpdir(), 'portfolio-empty-assets-'));
+  temporaryRoots.push(root);
+  await mkdir(join(root, 'content/public'), { recursive: true });
+  await writeFile(join(root, 'content/public/asset-manifest.json'), '{"assets":[]}');
+  return root;
+};
+
+afterEach(async () => {
+  await Promise.all(temporaryRoots.splice(0).map((root) => rm(root, { recursive: true, force: true })));
+});
+
+describe('empty asset materialization', () => {
+  it('creates an empty prepared-asset directory in the supplied repository root', async () => {
+    const root = await createScratchRepository();
+    await materializeEmptyAssetSet(root);
+    expect((await lstat(join(root, 'inputs/prepared-assets'))).isDirectory()).toBe(true);
+  });
+
+  it('rejects a symbolic-link prepared-asset directory', async () => {
+    const root = await createScratchRepository();
+    const target = join(root, 'outside');
+    await mkdir(target);
+    await mkdir(join(root, 'inputs'), { recursive: true });
+    await symlink(target, join(root, 'inputs/prepared-assets'));
+    await expect(materializeEmptyAssetSet(root)).rejects.toThrow(/non-symlink directory/i);
+  });
+
+  it('rejects unexpected prepared-asset members in its supplied repository root', async () => {
+    const root = await createScratchRepository();
+    const preparedAssetsPath = join(root, 'inputs/prepared-assets');
+    await mkdir(preparedAssetsPath, { recursive: true });
+    await writeFile(join(preparedAssetsPath, 'unexpected.webp'), 'not an asset');
+    await expect(materializeEmptyAssetSet(root)).rejects.toThrow(/must be empty/i);
+  });
+
+  it('rejects a prepared-asset directory replaced after its identity was captured', async () => {
+    const root = await createScratchRepository();
+    const preparedAssetsPath = join(root, 'inputs/prepared-assets');
+    await mkdir(preparedAssetsPath, { recursive: true });
+    const original = await lstat(preparedAssetsPath);
+    await rm(preparedAssetsPath, { recursive: true });
+    await mkdir(preparedAssetsPath);
+    await expect(assertPreparedAssetDirectoryIdentity(preparedAssetsPath, original))
+      .rejects.toThrow(/identity changed/i);
+  });
+});