feat(adapter-fetch): Add support for handling binary data

packages/@pollyjs/adapter-fetch/package.json

@@ -42,7 +42,9 @@
   "dependencies": {
     "@pollyjs/adapter": "^4.2.1",
     "@pollyjs/utils": "^4.1.0",
-    "detect-node": "^2.0.4"
+    "buffer": "^5.6.0",
+    "detect-node": "^2.0.4",
+    "to-arraybuffer": "^1.0.1"
   },
   "devDependencies": {
     "@pollyjs/core": "^4.2.1",

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

@@ -1,7 +1,10 @@
 import Adapter from '@pollyjs/adapter';
 import isNode from 'detect-node';
+import { Buffer } from 'buffer/';
+import bufferToArrayBuffer from 'to-arraybuffer';
 
 import serializeHeaders from './utils/serializer-headers';
+import isBufferUtf8Representable from './utils/is-buffer-utf8-representable';
 
 const { defineProperty } = Object;
 const IS_STUBBED = Symbol();
@@ -164,10 +167,14 @@ export default class FetchAdapter extends Adapter {
       }
     ]);
 
+    const buffer = Buffer.from(await response.arrayBuffer());
+    const isBinaryBuffer = !isBufferUtf8Representable(buffer);
+
     return {
       statusCode: response.status,
       headers: serializeHeaders(response.headers),
-      body: await response.text()
+      body: buffer.toString(isBinaryBuffer ? 'hex' : 'utf8'),
+      isBinary: isBinaryBuffer
     };
   }
 
@@ -199,11 +206,16 @@ export default class FetchAdapter extends Adapter {
     }
 
     const { absoluteUrl, response: pollyResponse } = pollyRequest;
-    const { statusCode } = pollyResponse;
-    const responseBody =
-      statusCode === 204 && pollyResponse.body === ''
-        ? null
-        : pollyResponse.body;
+    const { statusCode, body, isBinary } = pollyResponse;
+
+    let responseBody = body;
+
+    if (statusCode === 204 && responseBody === '') {
+      responseBody = null;
+    } else if (isBinary) {
+      responseBody = bufferToArrayBuffer(Buffer.from(body, 'hex'));
+    }
+
     const response = new Response(responseBody, {
       status: statusCode,
       headers: pollyResponse.headers

packages/@pollyjs/adapter-fetch/src/utils/is-buffer-utf8-representable.js

@@ -0,0 +1,12 @@
+import { Buffer } from 'buffer/';
+
+/**
+ * Determine if the given buffer is utf8.
+ * @param {Buffer} buffer
+ */
+export default function isBufferUtf8Representable(buffer) {
+  const utfEncodedBuffer = buffer.toString('utf8');
+  const reconstructedBuffer = Buffer.from(utfEncodedBuffer, 'utf8');
+
+  return reconstructedBuffer.equals(buffer);
+}

packages/@pollyjs/adapter-fetch/tests/integration/adapter-test.js

@@ -5,6 +5,7 @@ import adapterTests from '@pollyjs-tests/integration/adapter-tests';
 import adapterPollyTests from '@pollyjs-tests/integration/adapter-polly-tests';
 import adapterBrowserTests from '@pollyjs-tests/integration/adapter-browser-tests';
 import adapterIdentifierTests from '@pollyjs-tests/integration/adapter-identifier-tests';
+import { Buffer } from 'buffer/';
 
 import FetchAdapter from '../../src';
 import pollyConfig from '../utils/polly-config';
@@ -103,6 +104,39 @@ describe('Integration | Fetch Adapter', function() {
     expect(error.message).to.contain('The user aborted a request.');
   });
 
+  it('should be able to download binary content', async function() {
+    this.timeout(10000);
+
+    const fetch = async () =>
+      Buffer.from(
+        await this.fetch('https://placekitten.com/32/32').then(res =>
+          res.arrayBuffer()
+        )
+      );
+
+    this.polly.disconnectFrom(FetchAdapter);
+
+    const nativeResponseBuffer = await fetch();
+
+    this.polly.connectTo(FetchAdapter);
+
+    const recordedResponseBuffer = await fetch();
+
+    const { recordingName, config } = this.polly;
+
+    await this.polly.stop();
+    this.polly = new Polly(recordingName, config);
+    this.polly.replay();
+
+    const replayedResponseBuffer = await fetch();
+
+    expect(nativeResponseBuffer.equals(recordedResponseBuffer)).to.equal(true);
+    expect(recordedResponseBuffer.equals(replayedResponseBuffer)).to.equal(
+      true
+    );
+    expect(nativeResponseBuffer.equals(replayedResponseBuffer)).to.equal(true);
+  });
+
   describe('Request', function() {
     it('should support Request objects', async function() {
       const { server } = this.polly;

yarn.lock

@@ -3914,6 +3914,14 @@ buffer@^4.3.0:
     ieee754 "^1.1.4"
     isarray "^1.0.0"
 
+buffer@^5.6.0:
+  version "5.6.0"
+  resolved "https://registry.yarnpkg.com/buffer/-/buffer-5.6.0.tgz#a31749dc7d81d84db08abf937b6b8c4033f62786"
+  integrity sha512-/gDYp/UtU0eA1ys8bOs9J6a+E/KWIY+DZ+Q2WESNUA0jFRsJOc0SNUO6xJ5SGA1xueg3NL65W6s+NY5l9cunuw==
+  dependencies:
+    base64-js "^1.0.2"
+    ieee754 "^1.1.4"
+
 builtin-modules@^3.1.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/builtin-modules/-/builtin-modules-3.1.0.tgz#aad97c15131eb76b65b50ef208e7584cd76a7484"
@@ -13542,7 +13550,7 @@ to-array@0.1.4:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/to-array/-/to-array-0.1.4.tgz#17e6c11f73dd4f3d74cda7a4ff3238e9ad9bf890"
 
-to-arraybuffer@^1.0.0:
+to-arraybuffer@^1.0.0, to-arraybuffer@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/to-arraybuffer/-/to-arraybuffer-1.0.1.tgz#7d229b1fcc637e466ca081180836a7aabff83f43"