feat: 🎸 export fsa() factory

Author: streamich

src/fsa/__tests__/scenarios.test.ts

@@ -1,7 +1,8 @@
 import { Superblock } from '../../core/Superblock';
-import { coreToFsa } from '../index';
+import { coreToFsa, fsa } from '../index';
 import { CoreFileSystemDirectoryHandle } from '../CoreFileSystemDirectoryHandle';
 import { onlyOnNode20 } from '../../__tests__/util';
+import { fileURLToPath } from 'url';
 
 onlyOnNode20('coreToFsa scenarios', () => {
   test('can create FSA from empty Superblock', () => {
@@ -21,6 +22,38 @@ onlyOnNode20('coreToFsa scenarios', () => {
     expect(fsa).toBeInstanceOf(CoreFileSystemDirectoryHandle);
   });
 
+  test('can create FSA using fsa() helper', async () => {
+    const {dir, core} = fsa({ mode: 'readwrite' });
+    core.fromJSON({
+      'documents/readme.txt': 'Welcome!',
+      'photos/vacation.jpg': Buffer.from('fake-jpg-data'),
+      'empty-folder': null,
+    }, '/');
+    expect(dir).toBeInstanceOf(CoreFileSystemDirectoryHandle);
+    expect(dir.name).toBe('');
+    const dir2 = await dir.getDirectoryHandle('documents');
+    const file = await dir2.getFileHandle('readme.txt');
+    const fileContent = await file.getFile();
+    expect(await fileContent.text()).toBe('Welcome!');
+  });
+
+  test('can create a a file folder in empty filesystem', async () => {
+    const {dir, core} = fsa({ mode: 'readwrite' });
+    expect(core.toJSON()).toEqual({});
+    const dir2 = await dir.getDirectoryHandle('new-folder', { create: true });
+    expect(core.toJSON()).toEqual({
+      '/new-folder': null,
+    });
+    const file = await dir2.getFileHandle('file.txt', { create: true });
+    expect(core.toJSON()).toEqual({
+      '/new-folder/file.txt': '',
+    });
+    await (await file.createWritable()).write('Hello, world!');
+    expect(core.toJSON()).toEqual({
+      '/new-folder/file.txt': 'Hello, world!',
+    });
+  });
+
   test('can navigate filesystem structure', async () => {
     const core = Superblock.fromJSON(
       {

src/fsa/index.ts

@@ -20,3 +20,18 @@ export const coreToFsa = (
 ): CoreFileSystemDirectoryHandle => {
   return new CoreFileSystemDirectoryHandle(core, dirPath, ctx);
 };
+
+/**
+ * Create a new instance of an in-memory File System Access API
+ * implementation rooted at the root directory of the filesystem.
+ *
+ * @param ctx Optional context for the File System Access API.
+ * @returns A File System Access API implementation `dir` rooted at
+ *     the root directory of the filesystem, as well as the `core`
+ *     file system itself.
+ */
+export const fsa = (ctx?: Partial<CoreFsaContext>) => {
+  const core = new Superblock();
+  const dir = new CoreFileSystemDirectoryHandle(core, '/', ctx);
+  return {dir, core};
+};