Fix handling of dynamic URLs in the test builder

Fix the test builder to call the URL factory function before each test.

Before this change, the URL produced by the first test was used,
which caused problems in tests that were creating new entities
before each test, e.g. `lt.describe.whenCalledByUser`.

Author: clark0x

lib/helpers.js

@@ -156,7 +156,7 @@ _describe.whenCalledRemotely = function(verb, url, data, cb) {
   describe(verb.toUpperCase() + ' ' + urlStr, function() {
     beforeEach(function(cb) {
       if(typeof url === 'function') {
-        url = url.call(this);
+        this.url = url.call(this);
       }
       this.remotely = true;
       this.verb = verb.toUpperCase();

test/test.js

@@ -72,5 +72,18 @@ describe('helpers', function () {
         });
       });
     });
+    helpers.describe.staticMethod('findById', function() {
+      helpers.beforeEach.givenModel('xxx-test-model', {foo: 'bar'});
+      helpers.describe.whenCalledRemotely('GET', function () {
+        return '/xxx-test-models/' + this['xxx-test-model'].id;
+      }, function() {
+        it('should retrieve the expected model in the first test', function () {
+          assert.equal(this.res.body.id, this['xxx-test-model'].id);
+        });
+        it('should retrieve the expected model in subsequent tests', function () {
+          assert.equal(this.res.body.id, this['xxx-test-model'].id);
+        });
+      });
+    });
   });
 });