covered additional listener case

Author: William Armiros

packages/core/lib/patchers/http_p.js

@@ -161,13 +161,17 @@ function enableCapture(module, downstreamXRayEnabled, subsegmentCallback) {
 
         var cause = Utils.getCauseTypeFromHttpStatus(res.statusCode);
 
+        console.log('closing!!');
+
         if (cause)
           subsegment[cause] = true;
 
         subsegment.addRemoteRequestData(res.req, res, !!downstreamXRayEnabled);
         subsegment.close();
       });
 
+      // console.log(res.req.listenerCount('response'));
+
       if (typeof callback === 'function') {
         if (contextUtils.isAutomaticMode()) {
           var session = contextUtils.getNamespace();
@@ -179,10 +183,11 @@ function enableCapture(module, downstreamXRayEnabled, subsegmentCallback) {
         } else {
           callback(res);
         }
-        // if no callback provided by user application, then we consume the response
-        // so the 'end' event fires
+        // if no callback provided by user application, AND no explicit response listener
+        // added by user application, then we consume the response so the 'end' event fires
         // See: https://nodejs.org/api/http.html#http_class_http_clientrequest
-      } else {
+      } else if (res.req && res.req.listenerCount('response') === 0) {
+        console.log('resuming!');
         res.resume();
       }
     });

packages/core/test/unit/patchers/http_p.test.js

@@ -137,6 +137,7 @@ describe('HTTP/S', function() {
 
         fakeRequest = buildFakeRequest();
         fakeResponse = buildFakeResponse();
+        fakeResponse.req = fakeRequest;
 
         httpClient = { request: function(...args) {
           const callback = args[typeof args[1] === 'object' ? 2 : 1];
@@ -171,6 +172,12 @@ describe('HTTP/S', function() {
         resumeSpy.should.not.have.been.called;
       });
 
+      it('should not consume the response if a response listener is provided by user', function() {
+        fakeRequest.on('response', () => {});
+        capturedHttp.request(httpOptions);
+        resumeSpy.should.not.have.been.called;
+      });
+
       it('should create a new subsegment with name as hostname', function() {
         var options = {hostname: 'hostname', path: '/'};
         capturedHttp.request(options);