feat: 🎸 implement .getFile() method

src/node-to-fsa/NodeFileSystemFileHandle.ts

@@ -1,6 +1,6 @@
 import { NodeFileSystemHandle } from './NodeFileSystemHandle';
 import { NodeFileSystemSyncAccessHandle } from './NodeFileSystemSyncAccessHandle';
-import { basename, ctx as createCtx } from './util';
+import { basename, ctx as createCtx, newNotAllowedError } from './util';
 import type { NodeFsaContext, NodeFsaFs } from './types';
 
 export class NodeFileSystemFileHandle extends NodeFileSystemHandle {
@@ -13,10 +13,30 @@ export class NodeFileSystemFileHandle extends NodeFileSystemHandle {
   }
 
   /**
+   * Returns a {@link Promise} which resolves to a {@link File} object
+   * representing the state on disk of the entry represented by the handle.
+   * 
    * @see https://developer.mozilla.org/en-US/docs/Web/API/FileSystemFileHandle/getFile
    */
   public async getFile(): Promise<File> {
-    throw new Error('Not implemented');
+    try {
+      const path = this.__path;
+      const promises = this.fs.promises;
+      const stats = await promises.stat(path);
+      const data = await promises.readFile(path);
+      const file = new File([data], this.name, {lastModified: stats.mtime.getTime()});
+      return file;
+    } catch (error) {
+      if (error instanceof DOMException) throw error;
+      if (error && typeof error === 'object') {
+        switch (error.code) {
+          case 'EPERM':
+          case 'EACCES':
+            throw newNotAllowedError();
+        }
+      }
+      throw error;
+    }
   }
 
   /**