fix: Handle failed arraybuffer instanceof checks (#393)

packages/@pollyjs/adapter-fetch/src/index.js

@@ -1,5 +1,5 @@
 import Adapter from '@pollyjs/adapter';
-import { isBufferUtf8Representable } from '@pollyjs/utils';
+import { cloneArrayBuffer, isBufferUtf8Representable } from '@pollyjs/utils';
 import isNode from 'detect-node';
 import { Buffer } from 'buffer/';
 import bufferToArrayBuffer from 'to-arraybuffer';
@@ -167,7 +167,24 @@ export default class FetchAdapter extends Adapter {
       }
     ]);
 
-    const buffer = Buffer.from(await response.arrayBuffer());
+    let arrayBuffer = await response.arrayBuffer();
+
+    /*
+      If the returned array buffer is not an instance of the global ArrayBuffer,
+      clone it in order to pass Buffer.from's instanceof check. This can happen
+      when using this adapter with a different context.
+
+      https://github.com/feross/buffer/issues/289
+    */
+    if (
+      arrayBuffer &&
+      !(arrayBuffer instanceof ArrayBuffer) &&
+      'byteLength' in arrayBuffer
+    ) {
+      arrayBuffer = cloneArrayBuffer(arrayBuffer);
+    }
+
+    const buffer = Buffer.from(arrayBuffer);
     const isBinaryBuffer = !isBufferUtf8Representable(buffer);
 
     return {

packages/@pollyjs/adapter-xhr/src/index.js

@@ -1,6 +1,6 @@
 import fakeXhr from '@offirgolan/nise/lib/fake-xhr';
 import Adapter from '@pollyjs/adapter';
-import { isBufferUtf8Representable } from '@pollyjs/utils';
+import { cloneArrayBuffer, isBufferUtf8Representable } from '@pollyjs/utils';
 import { Buffer } from 'buffer/';
 import bufferToArrayBuffer from 'to-arraybuffer';
 
@@ -112,7 +112,24 @@ export default class XHRAdapter extends Adapter {
 
     // responseType will either be `arraybuffer` or `text`
     if (xhr.responseType === 'arraybuffer') {
-      const buffer = Buffer.from(xhr.response);
+      let arrayBuffer = xhr.response;
+
+      /*
+        If the returned array buffer is not an instance of the global ArrayBuffer,
+        clone it in order to pass Buffer.from's instanceof check. This can happen
+        when using this adapter with a different context.
+
+        https://github.com/feross/buffer/issues/289
+      */
+      if (
+        arrayBuffer &&
+        !(arrayBuffer instanceof ArrayBuffer) &&
+        'byteLength' in arrayBuffer
+      ) {
+        arrayBuffer = cloneArrayBuffer(arrayBuffer);
+      }
+
+      const buffer = Buffer.from(arrayBuffer);
 
       isBinary = !isBufferUtf8Representable(buffer);
       body = buffer.toString(isBinary ? 'hex' : 'utf8');

packages/@pollyjs/utils/src/index.js

@@ -17,3 +17,4 @@ export { default as URL } from './utils/url';
 export {
   default as isBufferUtf8Representable
 } from './utils/is-buffer-utf8-representable';
+export { default as cloneArrayBuffer } from './utils/clone-arraybuffer';

packages/@pollyjs/utils/src/utils/clone-arraybuffer.js

@@ -0,0 +1,12 @@
+/**
+ * Clone an array buffer
+ *
+ * @param {ArrayBuffer} arrayBuffer
+ */
+export default function cloneArrayBuffer(arrayBuffer) {
+  const clonedArrayBuffer = new ArrayBuffer(arrayBuffer.byteLength);
+
+  new Uint8Array(clonedArrayBuffer).set(new Uint8Array(arrayBuffer));
+
+  return clonedArrayBuffer;
+}