Pass dispatcher options to global fetch (#653)

* Pass dispatcher options to global fetch

* Pass down all args to base fetch

Author: Kruspe

sdk_contrib/fetch/lib/fetch_p.js

@@ -116,7 +116,7 @@ const enableCapture = function enableCapture(baseFetchFunction, requestClass, do
       const requestClone = request.clone();
       let response;
       try {
-        response = await baseFetchFunction(requestClone);
+        response = await baseFetchFunction(...args);
 
         if (thisSubsegmentCallback) {
           thisSubsegmentCallback(subsegment, requestClone, response);

sdk_contrib/fetch/test/unit/fetch_p.test.js

@@ -339,6 +339,17 @@ describe('Unit tests', function () {
       response.should.equal(stubValidResponse);
     });
 
+    it('resolves to response through proxy when fetch options are supplied', async function() {
+      const activeFetch = captureFetch(true);
+      const proxyStub = sinon.stub();
+      const request = new FetchRequest('https://www.foo.com/test');
+      const response = await activeFetch(request, {
+        dispatcher: proxyStub
+      });
+      stubFetch.should.have.been.calledOnceWith(request, {dispatcher: proxyStub});
+      response.should.equal(stubValidResponse);
+    });
+
     it('calls subsegmentCallback with error upon fetch throwing', async function () {
       const spyCallback = sandbox.spy();
       const activeFetch = captureFetch(true, spyCallback);