feat(node/fs): Add a createReadStream method to the FileHandle class

ext/node/polyfills/internal/fs/handle.ts

@@ -5,7 +5,7 @@
 
 import { EventEmitter } from "node:events";
 import { Buffer } from "node:buffer";
-import { Mode, promises, read, write } from "node:fs";
+import { createReadStream, Mode, promises, read, ReadStream, write } from "node:fs";
 export type { BigIntStats, Stats } from "ext:deno_node/_fs/_fs_stat.ts";
 import {
   BinaryOptionsArgument,
@@ -15,6 +15,7 @@ import {
 } from "ext:deno_node/_fs/_fs_common.ts";
 import { ftruncatePromise } from "ext:deno_node/_fs/_fs_ftruncate.ts";
 import { core } from "ext:core/mod.js";
+import { CreateReadStreamOptions } from "node:fs/promises";
 
 interface WriteResult {
   bytesWritten: number;
@@ -148,10 +149,17 @@ export class FileHandle extends EventEmitter {
   stat(options?: { bigint: boolean }): Promise<Stats | BigIntStats> {
     return fsCall(promises.fstat, this, options);
   }
+
   chmod(mode: Mode): Promise<void> {
     assertNotClosed(this, promises.chmod.name);
     return promises.chmod(this.#path, mode);
   }
+
+  createReadStream(options?: CreateReadStreamOptions): ReadStream {
+    assertNotClosed(this, createReadStream.name);
+    const opts = options as Omit<CreateReadStreamOptions, "encoding">;
+    return createReadStream(this.#path, opts);
+  }
 }
 
 function assertNotClosed(handle: FileHandle, syscall: string) {

tests/unit_node/_fs/_fs_handle_test.ts

@@ -217,3 +217,36 @@ Deno.test({
     await fileHandle.close();
   },
 });
+
+Deno.test(
+  "[node/fs filehandle.createReadStream] Create a read stream",
+  async function () {
+    const fileHandle = await fs.open(testData);
+    const stream = fileHandle.createReadStream();
+    const fileSize = (await fileHandle.stat()).size;
+
+    assertEquals(stream.bytesRead, 0);
+    assertEquals(stream.readable, true);
+
+    let bytesRead = 0;
+
+    stream.on("open", () => assertEquals(stream.bytesRead, 0));
+
+    stream.on("data", (data) => {
+      assertEquals(data instanceof Buffer, true);
+      assertEquals((data as Buffer).byteOffset % 8, 0);
+      bytesRead += data.length;
+      assertEquals(stream.bytesRead, bytesRead);
+    });
+
+    stream.on("end", () => {
+      assertEquals(stream.bytesRead, fileSize);
+      assertEquals(bytesRead, fileSize);
+    });
+
+    await new Promise((resolve) => {
+      stream.close(resolve);
+    });
+    await fileHandle.close();
+  },
+);