Adding tests fo verify tile queue management.

tests/Tile.html

@@ -53,6 +53,39 @@
         tearDown();
         
     }
+    
+    function test_Tile_draw(t) {
+        t.plan(6);
+        setUp();
+
+        var position = new OpenLayers.Pixel(10,20);
+        var bounds = new OpenLayers.Bounds(1,2,3,4);
+        var url = "bobob";
+        var size = new OpenLayers.Size(5,6);
+        
+        tile = new OpenLayers.Tile(layer, position, bounds, url, size);
+        var log = [];
+        tile.clear = function() {
+            log.push("clear");
+        }
+        tile.draw();
+        t.eq(log.length, 1, "Tile cleared before drawing");
+        
+        log = [];
+        tile.events.register("beforedraw", this, function() {
+            log.push("beforedraw");
+            return false;
+        });
+        var drawn = tile.draw();
+        t.eq(log[0], "clear", "tile cleared");
+        t.eq(log[1], "beforedraw", "beforedraw event fired");
+        t.eq(drawn, false, "tile not drawn when beforedraw listener returns false");
+        drawn = tile.draw(true);
+        t.eq(log.length, 2, "no beforedraw event fired and tile not cleared when draw called with 'deferred' argument set to true");
+        t.eq(drawn, true, "tile drawn when draw called with 'deferred' argument set to true");
+
+        tearDown();
+    }
 
     function test_Tile_destroy(t) {
         t.plan( 6 );