tests: check render error without engine-specific message

closes #3251

test/app.render.js

@@ -97,12 +97,10 @@ describe('app', function(){
 
         app.set('views', path.join(__dirname, 'fixtures'))
 
-        app.render('user.tmpl', function (err, str) {
-          // nextTick to prevent cyclic
-          process.nextTick(function(){
-            err.message.should.match(/Cannot read property '[^']+' of undefined/);
-            done();
-          });
+        app.render('user.tmpl', function (err) {
+          assert.ok(err)
+          assert.equal(err.name, 'RenderError')
+          done()
         })
       })
     })

test/res.render.js

@@ -105,12 +105,12 @@ describe('res', function(){
         });
 
         app.use(function(err, req, res, next){
-          res.end(err.message);
+          res.status(500).send('got error: ' + err.name)
         });
 
         request(app)
         .get('/')
-        .expect(/Cannot read property '[^']+' of undefined/, done);
+        .expect(500, 'got error: RenderError', done)
       })
     })
 
@@ -329,13 +329,15 @@ describe('res', function(){
 
         app.use(function(req, res){
           res.render('user.tmpl', function (err) {
-            res.end(err.message);
+            if (err) {
+              res.status(500).send('got error: ' + err.name)
+            }
           });
         });
 
         request(app)
         .get('/')
-        .expect(/Cannot read property '[^']+' of undefined/, done);
+        .expect(500, 'got error: RenderError', done)
       })
     })
   })

test/support/tmpl.js

@@ -13,6 +13,7 @@ module.exports = function renderFile(fileName, options, callback) {
       str = str.replace(variableRegExp, generateVariableLookup(options));
     } catch (e) {
       err = e;
+      err.name = 'RenderError'
     }
 
     callback(err, str);