add tests and finish off the functionality for switching between singleTile true and false

lib/OpenLayers/Layer/Grid.js

@@ -311,14 +311,7 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
         this.tileQueue = [];
         this._removeBackBuffer = OpenLayers.Function.bind(this.removeBackBuffer, this);
 
-        if (this.removeBackBufferDelay === null) {
-            this.removeBackBufferDelay = this.singleTile ? 0 : 2500;
-        }
-        
-        if (this.className === null) {
-            this.className = this.singleTile ? 'olLayerGridSingleTile' :
-                                               'olLayerGrid';
-        }
+        this.initProperties();
 
         if (!OpenLayers.Animation.isNative) {
             this.deferMoveGriddedTiles = OpenLayers.Function.bind(function() {
@@ -330,6 +323,22 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
         this.rowSign = this.tileOriginCorner.substr(0, 1) === "t" ? 1 : -1;
     },
 
+    /**
+     * Method: initProperties
+     * Set any properties that depend on the value of singleTile.
+     * Currently sets removeBackBufferDelay and className
+     */
+    initProperties: function() {
+        if (this.options.removeBackBufferDelay === undefined) {
+            this.removeBackBufferDelay = this.singleTile ? 0 : 2500;
+        }
+
+        if (this.options.className === undefined) {
+            this.className = this.singleTile ? 'olLayerGridSingleTile' :
+                                               'olLayerGrid';
+        }
+    },
+
     /**
      * Method: setMap
      *
@@ -406,7 +415,8 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
     */
     addOptions: function (newOptions, reinitialize) {
         OpenLayers.Layer.HTTPRequest.prototype.addOptions.apply(this, arguments);
-        if (newOptions.singleTile !== undefined) {
+        if (this.map && newOptions.singleTile !== undefined) {
+            this.initProperties();
             this.clearGrid();
             if (newOptions.singleTile === true) {
                 this.setTileSize();