fix($http): apply transformResponse when data is empty (for non-HEAD requests)

Fixes #12976

Author: gkalpak

src/ng/http.js

@@ -999,7 +999,7 @@ function $HttpProvider() {
       function transformResponse(response) {
         // make a copy since the response must be cacheable
         var resp = extend({}, response);
-        if (!response.data) {
+        if (config.method === 'HEAD') {
           resp.data = response.data;
         } else {
           resp.data = transformData(response.data, response.headers, response.status, config.transformResponse);

test/ng/httpSpec.js

@@ -1391,6 +1391,31 @@ describe('$http', function() {
           expect(callback).toHaveBeenCalledOnce();
           expect(callback.mostRecentCall.args[0]).toBe('RESP-FIRST:V1');
         });
+
+
+        it('should not apply `transformResponse` on `HEAD` requests', function() {
+          var transformResponse = jasmine.createSpy('transformResponse');
+
+          $httpBackend.expect('HEAD', '/url').respond(200, 'Hello, world !');
+          $http.head('/url', {transformResponse: transformResponse});
+          $httpBackend.flush();
+
+          expect(transformResponse).not.toHaveBeenCalled();
+        });
+
+
+        it('should apply `transformResponse` on non-`HEAD` requests with empty response',
+          function() {
+            var transformResponse = jasmine.createSpy('transformResponse');
+
+            $httpBackend.expect('GET', '/url').respond(200, null);
+            $http.get('/url', {transformResponse: transformResponse});
+            $httpBackend.flush();
+
+            expect(transformResponse).toHaveBeenCalledOnce();
+            expect(transformResponse.mostRecentCall.args[0]).toBe(null);
+          }
+        );
       });
     });