Added test to ensure that XHR adapter does not read cookies if xsrfCookieName is null

test/specs/xsrf.spec.js

@@ -1,3 +1,5 @@
+var cookies = require('../../lib/helpers/cookies');
+
 describe('xsrf', function () {
   beforeEach(function () {
     jasmine.Ajax.install();
@@ -41,6 +43,19 @@ describe('xsrf', function () {
     });
   });
 
+  it('should not read cookies at all if xsrfCookieName is null', function (done) {
+    spyOn(cookies, "read");
+
+    axios('/foo', {
+      xsrfCookieName: null
+    });
+
+    getAjaxRequest().then(function (request) {
+      expect(cookies.read).not.toHaveBeenCalled();
+      done();
+    });
+  });
+
   it('should not set xsrf header for cross origin', function (done) {
     document.cookie = axios.defaults.xsrfCookieName + '=12345';