fix: Response.arrayBuffer() doesn't return promise (#7618)

cli/tests/unit/response_test.ts

+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { unitTest, assert, assertEquals } from "./test_util.ts";
+
+unitTest(async function responseText() {
+  const response = new Response("hello world");
+  const textPromise = response.text();
+  assert(textPromise instanceof Promise);
+  const text = await textPromise;
+  assert(typeof text === "string");
+  assertEquals(text, "hello world");
+});
+
+unitTest(async function responseArrayBuffer() {
+  const response = new Response(new Uint8Array([1, 2, 3]));
+  const arrayBufferPromise = response.arrayBuffer();
+  assert(arrayBufferPromise instanceof Promise);
+  const arrayBuffer = await arrayBufferPromise;
+  assert(arrayBuffer instanceof ArrayBuffer);
+  assertEquals(new Uint8Array(arrayBuffer), new Uint8Array([1, 2, 3]));
+});
+
+unitTest(async function responseJson() {
+  const response = new Response('{"hello": "world"}');
+  const jsonPromise = response.json();
+  assert(jsonPromise instanceof Promise);
+  const json = await jsonPromise;
+  assert(json instanceof Object);
+  assertEquals(json, { hello: "world" });
+});
+
+unitTest(async function responseBlob() {
+  const response = new Response(new Uint8Array([1, 2, 3]));
+  const blobPromise = response.blob();
+  assert(blobPromise instanceof Promise);
+  const blob = await blobPromise;
+  assert(blob instanceof Blob);
+  assertEquals(blob, new Blob([new Uint8Array([1, 2, 3])]));
+});
+
+unitTest(async function responseFormData() {
+  const input = new FormData();
+  input.append("hello", "world");
+  const response = new Response(input, {
+    headers: { "content-type": "application/x-www-form-urlencoded" },
+  });
+  const formDataPromise = response.formData();
+  assert(formDataPromise instanceof Promise);
+  const formData = await formDataPromise;
+  assert(formData instanceof FormData);
+  assertEquals(formData, input);
+});

cli/tests/unit/unit_tests.ts

@@ -54,6 +54,7 @@ import "./remove_test.ts";
 import "./rename_test.ts";
 import "./request_test.ts";
 import "./resources_test.ts";
+import "./response_test.ts";
 import "./signal_test.ts";
 import "./stat_test.ts";
 import "./stdio_test.ts";

op_crates/fetch/26_fetch.js

@@ -869,7 +869,7 @@
       if (this._bodySource instanceof ReadableStream) {
         return bufferFromStream(this._bodySource.getReader(), this.#size);
       }
-      return bodyToArrayBuffer(this._bodySource);
+      return Promise.resolve(bodyToArrayBuffer(this._bodySource));
     }
   }