Deltas were causing canvas centering

test/test_viewport_module.js

 /*
 This file is part of the Juju GUI, which lets users view and manage Juju
 environments within a graphical interface (https://launchpad.net/juju-gui).
 Copyright (C) 2012-2013 Canonical Ltd.
 
 This program is free software: you can redistribute it and/or modify it under
 the terms of the GNU Affero General Public License version 3, as published by
 the Free Software Foundation.
 
 This program is distributed in the hope that it will be useful, but WITHOUT
@@ skipping 77 matching lines @@
     view.resized();
     events.should.eql(
         ['beforePageSizeRecalculation',
          'setAllTheDimensions called',
          'afterPageSizeRecalculation']);
   });
 });
 
 describe('views.ViewportModule.setAllTheDimensions', function() {
   var views, Y, testUtils, view, width, height, canvas, svg, topo, zoomPlane,
-      eventFired;
+      eventFired, dimentions;
   before(function(done) {
     Y = YUI(GlobalConfig).use(['node', 'juju-views', 'juju-tests-utils'],
         function(Y) {
           views = Y.namespace('juju.views');
           testUtils = Y.namespace('juju-tests').utils;
           done();
         });
   });
 
   beforeEach(function() {
     height = Math.floor(Math.random() * 1000);
     width = Math.floor(Math.random() * 1000);
     // Build test doubles that record height and width settings.
     topo = {
+      get: function() {
+        return [width + 1, height + 1];

[benji, 2013/09/05 17:08:49]

A comment as to why the "+ 1"s are needed would be nice.

+      },
       vis: {},
       fire: function(evt) {
         eventFired = evt;
       }
     };
     topo.set = testUtils.setter(topo);
     topo.vis.attr = testUtils.setter(topo.vis);
     view = new views.ViewportModule();
     canvas = {style: {}};
     canvas.setStyles = function(styles) {
       Y.mix(canvas.style, styles, true);
     };
     zoomPlane = {};
     zoomPlane.setAttribute = testUtils.setter(zoomPlane);
     svg = {};
     svg.setAttribute = testUtils.setter(svg);
-    var dimentions = {
+    dimentions = {
       height: height,
       width: width
     };
     // Since all of the tests inspect the output of setAllTheDimensions, we can
     // just call it here and the tests will just contain assertions.
     view.setAllTheDimensions(dimentions, canvas, svg, topo, zoomPlane);
   });
 
   it('should set canvas dimensions', function() {
     assert.equal(canvas.style.width, width + 'px');
@@ skipping 15 matching lines @@
   });
 
   it('should set topo.vis dimensions', function() {
     assert.equal(topo.vis.width, width);
     assert.equal(topo.vis.height, height);
   });
 
   it('should center canvas', function() {
     assert.equal(eventFired, 'panToCenter');
   });
+
+  it('should not center canvas if no changes', function() {
+    topo.get = function() {
+      return [width, height];
+    };
+    eventFired = false;
+    view.setAllTheDimensions(dimentions, canvas, svg, topo, zoomPlane);
+    assert.equal(eventFired, false);
+  });
 });