feat(util-stream-node): use TextDecoder

Author: AllanZhengYP

packages/util-stream-node/src/sdk-stream-mixin.spec.ts

@@ -1,6 +1,7 @@
 import { SdkStreamMixin } from "@aws-sdk/types";
 import { fromArrayBuffer } from "@aws-sdk/util-buffer-from";
 import { PassThrough, Readable, Writable } from "stream";
+import util from "util";
 
 import { sdkStreamMixin } from "./sdk-stream-mixin";
 
@@ -92,6 +93,23 @@ describe(sdkStreamMixin.name, () => {
       }
     );
 
+    it.each(["ibm866", "iso-8859-2", "koi8-r", "macintosh", "windows-874", "gbk", "gb18030", "euc-jp"])(
+      "should transform the stream to string with TextDecoder config %s",
+      async (encoding) => {
+        jest.spyOn(util, "TextDecoder").mockImplementation(
+          () =>
+            ({
+              decode: jest.fn(),
+            } as any)
+        );
+        (fromArrayBuffer as jest.Mock).mockReturnValue({ toString: toStringMock });
+        const sdkStream = sdkStreamMixin(passThrough);
+        await writeDataToStream(passThrough, [Buffer.from("foo")]);
+        await sdkStream.transformToString(encoding);
+        expect(util.TextDecoder).toBeCalledWith(encoding);
+      }
+    );
+
     it("should fail any subsequent tranform calls", async () => {
       const sdkStream = sdkStreamMixin(passThrough);
       await writeDataToStream(passThrough, [Buffer.from("foo")]);

packages/util-stream-node/src/sdk-stream-mixin.ts

@@ -2,6 +2,7 @@ import { streamCollector } from "@aws-sdk/node-http-handler";
 import { SdkStream, SdkStreamMixin } from "@aws-sdk/types";
 import { fromArrayBuffer } from "@aws-sdk/util-buffer-from";
 import { Readable } from "stream";
+import { TextDecoder } from "util";
 
 const ERR_MSG_STREAM_HAS_BEEN_TRANSFORMED = "The stream has already been transformed.";
 
@@ -30,7 +31,12 @@ export const sdkStreamMixin = (stream: unknown): SdkStream<Readable> => {
     transformToByteArray,
     transformToString: async (encoding?: string) => {
       const buf = await transformToByteArray();
-      return fromArrayBuffer(buf.buffer, buf.byteOffset, buf.byteLength).toString(encoding);
+      if (encoding === undefined || Buffer.isEncoding(encoding)) {
+        return fromArrayBuffer(buf.buffer, buf.byteOffset, buf.byteLength).toString(encoding);
+      } else {
+        const decoder = new TextDecoder(encoding);
+        return decoder.decode(buf);
+      }
     },
     transformToWebStream: () => {
       if (transformed) {