fix(adapter-fetch): Correctly handle Request instance passed into fetch

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

@@ -5,6 +5,7 @@ import serializeHeaders from './utils/serializer-headers';
 
 const { defineProperty } = Object;
 const IS_STUBBED = Symbol();
+const REQUEST_ARGUMENTS = Symbol();
 
 export default class FetchAdapter extends Adapter {
   static get name() {
@@ -26,23 +27,72 @@ export default class FetchAdapter extends Adapter {
       );
     }
 
-    ['fetch', 'Response', 'Headers'].forEach(key =>
+    ['fetch', 'Request', 'Response', 'Headers'].forEach(key =>
       this.assert(`${key} global not found.`, !!(context && context[key]))
     );
     this.assert(
       'Running concurrent fetch adapters is unsupported, stop any running Polly instances.',
-      !context.fetch[IS_STUBBED]
+      !context.fetch[IS_STUBBED] && !context.Request[IS_STUBBED]
     );
 
-    this.native = context.fetch;
+    this.nativeFetch = context.fetch;
+    this.NativeRequest = context.Request;
+
+    /*
+      Patch the Request class so we can store all the passed in options. This
+      allows us the access the `body` directly instead of having to do
+      `await req.blob()` as well as not having to hard code each option we want
+      to extract from the Request instance.
+    */
+    class ExtendedRequest extends context.Request {
+      constructor(url, options) {
+        super(url, options);
+
+        let args;
+
+        options = options || {};
+
+        /*
+          The Request constructor can receive another Request instance as
+          the first argument so we use its arguments and merge it with the
+          new options.
+        */
+        if (url instanceof ExtendedRequest) {
+          const reqArgs = url[REQUEST_ARGUMENTS];
+
+          args = { ...reqArgs, options: { ...reqArgs.options, ...options } };
+        } else {
+          args = { url, options };
+        }
+
+        defineProperty(this, REQUEST_ARGUMENTS, { value: args });
+      }
+
+      clone() {
+        return new ExtendedRequest(this);
+      }
+    }
+
+    context.Request = ExtendedRequest;
+    defineProperty(context.Request, IS_STUBBED, { value: true });
 
     context.fetch = (url, options = {}) => {
+      let respond;
+
       // Support Request object
-      if (typeof url === 'object' && 'url' in url) {
-        url = url.url;
+      if (url instanceof ExtendedRequest) {
+        const req = url;
+        const reqArgs = req[REQUEST_ARGUMENTS];
+
+        url = reqArgs.url;
+        options = { ...reqArgs.options, ...options };
+
+        // If a body exists in the Request instance, mimic reading the body
+        if ('body' in reqArgs.options) {
+          defineProperty(req, 'bodyUsed', { value: true });
+        }
       }
 
-      let respond;
       const promise = new Promise((resolve, reject) => {
         respond = ({ response, error }) => {
           if (error) {
@@ -68,14 +118,20 @@ export default class FetchAdapter extends Adapter {
   }
 
   onDisconnect() {
-    this.options.context.fetch = this.native;
-    this.native = null;
+    const { context } = this.options;
+
+    context.fetch = this.nativeFetch;
+    context.Request = this.NativeRequest;
+
+    this.nativeFetch = null;
+    this.NativeRequest = null;
   }
 
   async passthroughRequest(pollyRequest) {
+    const { context } = this.options;
     const { options } = pollyRequest.requestArguments;
 
-    const response = await this.native.apply(global, [
+    const response = await this.nativeFetch.apply(context, [
       pollyRequest.url,
       {
         ...options,

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

@@ -7,6 +7,7 @@ import adapterBrowserTests from '@pollyjs-tests/integration/adapter-browser-test
 import FetchAdapter from '../../src';
 import pollyConfig from '../utils/polly-config';
 
+class MockRequest {}
 class MockResponse {}
 class MockHeaders {}
 
@@ -29,16 +30,6 @@ describe('Integration | Fetch Adapter', function() {
     expect(res.status).to.equal(200);
   });
 
-  it('should support Request objects', async function() {
-    const { server } = this.polly;
-
-    server.any(this.recordUrl()).intercept((_, res) => res.sendStatus(200));
-
-    const res = await this.fetch(new Request(this.recordUrl()));
-
-    expect(res.status).to.equal(200);
-  });
-
   it('should support array of key/value pair headers', async function() {
     const { server } = this.polly;
     let headers;
@@ -57,29 +48,129 @@ describe('Integration | Fetch Adapter', function() {
     expect(res.status).to.equal(200);
     expect(headers).to.deep.equal({ 'content-type': 'application/json' });
   });
+
+  describe('Request', function() {
+    it('should support Request objects', async function() {
+      const { server } = this.polly;
+
+      server.any(this.recordUrl()).intercept((_, res) => res.sendStatus(200));
+
+      const res = await this.fetch(new Request(this.recordUrl()));
+
+      expect(res.status).to.equal(200);
+    });
+
+    it('should set bodyUsed to true if a body is present', async function() {
+      const { server } = this.polly;
+      const request = new Request('/', { method: 'POST', body: '{}' });
+
+      server.any().intercept((_, res) => res.sendStatus(200));
+
+      expect(request.bodyUsed).to.equal(false);
+      await this.fetch(request);
+      expect(request.bodyUsed).to.equal(true);
+    });
+
+    it('should not set bodyUsed to true if a body is not present', async function() {
+      const { server } = this.polly;
+      const request = new Request('/');
+
+      server.any().intercept((_, res) => res.sendStatus(200));
+
+      expect(request.bodyUsed).to.equal(false);
+      await this.fetch(request);
+      expect(request.bodyUsed).to.equal(false);
+    });
+
+    function testRequestOptions(createRequest, options) {
+      return async function() {
+        const { server } = this.polly;
+        let receivedOptions;
+
+        server.any().intercept((req, res) => {
+          receivedOptions = req.requestArguments.options;
+          res.sendStatus(200);
+        });
+
+        const res = await this.fetch(createRequest());
+
+        expect(res.status).to.equal(200);
+        expect(options).to.deep.equal(receivedOptions);
+      };
+    }
+
+    it(
+      'should handle no options',
+      testRequestOptions(() => new Request('/'), {})
+    );
+
+    it(
+      'should handle simple options',
+      testRequestOptions(
+        () =>
+          new Request('/', { method: 'POST', body: '{}', cache: 'no-cache' }),
+        { method: 'POST', body: '{}', cache: 'no-cache' }
+      )
+    );
+
+    it(
+      'should handle a cloned request',
+      testRequestOptions(
+        () => new Request('/', { method: 'POST', body: '{}' }).clone(),
+        { method: 'POST', body: '{}' }
+      )
+    );
+
+    it(
+      'should handle a request instance',
+      testRequestOptions(
+        () => new Request(new Request('/', { method: 'POST', body: '{}' })),
+        { method: 'POST', body: '{}' }
+      )
+    );
+
+    it(
+      'should handle a request instance with overrides',
+      testRequestOptions(
+        () =>
+          new Request(new Request('/', { method: 'POST', body: '{}' }), {
+            method: 'PATCH',
+            headers: { foo: 'bar' }
+          }),
+        { method: 'PATCH', headers: { foo: 'bar' }, body: '{}' }
+      )
+    );
+  });
 });
 
 describe('Integration | Fetch Adapter | Init', function() {
   describe('Context', function() {
-    it(`should assign context's fetch as the native fetch`, async function() {
+    it(`should assign context's fetch as the native fetch and Request as the native Request`, async function() {
       const polly = new Polly('context', { adapters: [] });
       const fetch = () => {};
       const adapterOptions = {
         fetch: {
-          context: { fetch, Response: MockResponse, Headers: MockHeaders }
+          context: {
+            fetch,
+            Request: MockRequest,
+            Response: MockResponse,
+            Headers: MockHeaders
+          }
         }
       };
 
-      polly.configure({
-        adapters: [FetchAdapter],
-        adapterOptions
-      });
+      polly.configure({ adapters: [FetchAdapter], adapterOptions });
 
-      expect(polly.adapters.get('fetch').native).to.equal(fetch);
-      expect(polly.adapters.get('fetch').native).to.not.equal(
+      expect(polly.adapters.get('fetch').nativeFetch).to.equal(fetch);
+      expect(polly.adapters.get('fetch').nativeFetch).to.not.equal(
         adapterOptions.fetch.context.fetch
       );
 
+      expect(polly.adapters.get('fetch').NativeRequest).to.equal(MockRequest);
+      expect(polly.adapters.get('fetch').NativeRequest).to.not.equal(
+        adapterOptions.fetch.context.Request
+      );
+
       expect(function() {
         polly.configure({
           adapterOptions: { fetch: { context: {} } }
@@ -89,7 +180,7 @@ describe('Integration | Fetch Adapter | Init', function() {
       await polly.stop();
     });
 
-    it('should throw when context, fetch, Response, and Headers are undefined', async function() {
+    it('should throw when context, fetch, Request, Response, and Headers are undefined', async function() {
       const polly = new Polly('context', { adapters: [] });
 
       polly.configure({
@@ -108,6 +199,7 @@ describe('Integration | Fetch Adapter | Init', function() {
             fetch: {
               context: {
                 fetch: undefined,
+                Request: MockRequest,
                 Response: MockResponse,
                 Headers: MockHeaders
               }
@@ -120,7 +212,27 @@ describe('Integration | Fetch Adapter | Init', function() {
         polly.configure({
           adapterOptions: {
             fetch: {
-              context: { fetch() {}, Response: undefined, Headers: MockHeaders }
+              context: {
+                fetch() {},
+                Request: undefined,
+                Response: MockResponse,
+                Headers: MockHeaders
+              }
+            }
+          }
+        });
+      }).to.throw(/Request global not found/);
+
+      expect(function() {
+        polly.configure({
+          adapterOptions: {
+            fetch: {
+              context: {
+                fetch() {},
+                Request: MockRequest,
+                Response: undefined,
+                Headers: MockHeaders
+              }
             }
           }
         });
@@ -132,6 +244,7 @@ describe('Integration | Fetch Adapter | Init', function() {
             fetch: {
               context: {
                 fetch() {},
+                Request: MockRequest,
                 Response: MockResponse,
                 Headers: undefined
               }

tests/integration/adapter-tests.js

@@ -208,7 +208,7 @@ export default function adapterTests() {
     expect(res.ok).to.be.true;
   });
 
-  describe('expired tests', () => {
+  describe('Expiration', () => {
     async function testExpiration() {
       const { persister, recordingId } = this.polly;
       const url = '/api';