diff --git a/tests/Layer/ArcGIS93Rest.html b/tests/Layer/ArcGIS93Rest.html
index 4f1a4c618d..4a57b70c12 100644
--- a/tests/Layer/ArcGIS93Rest.html
+++ b/tests/Layer/ArcGIS93Rest.html
@@ -190,31 +190,6 @@
  
     }
 
-    function test_Layer_AGS93_setOpacity (t) {
-        var params = {layers: "show:0,2"};
-        t.plan( 5 );
-
-        var map = new OpenLayers.Map('map');
-        map.projection = "xx";
-        tParams = { layers: 'show:0,2', 
-                   format: 'png'};
-        tOptions = { 'opacity': '0.5' };           
-        var tLayer = new OpenLayers.Layer.ArcGIS93Rest(name, url, tParams, tOptions);
-        map.addLayer(tLayer);
-        map.zoomToMaxExtent();
-        t.eq(tLayer.opacity, "0.5", "Opacity is set correctly");
-        t.eq(parseFloat(tLayer.div.firstChild.style.opacity), 0.5, "Opacity on tile is correct");
-        tLayer.setOpacity("0.6");
-        t.eq(tLayer.opacity, "0.6", "setOpacity works properly");
-        t.eq(parseFloat(tLayer.div.firstChild.style.opacity), 0.6, "Opacity on tile is changed correctly");
-        var pixel = new OpenLayers.Pixel(5,6);
-        var tile = tLayer.addTile(new OpenLayers.Bounds(1,2,3,4), pixel);
-        tile.draw();
-        t.eq(parseFloat(tile.imgDiv.style.opacity), 0.6, "Tile opacity is set correctly");
-
-        map.destroy();
-    }    
-    
     function test_Layer_AGS93_noGutters (t) { 
         t.plan(2);
         var map = new OpenLayers.Map('map');
diff --git a/tests/Layer/Grid.html b/tests/Layer/Grid.html
index 0c5c747559..eae762735c 100644
--- a/tests/Layer/Grid.html
+++ b/tests/Layer/Grid.html
@@ -639,6 +639,38 @@
         t.eq( layer.grid, null, "layer.grid is null after destroy" );
         t.eq( layer.tileSize, null, "layer.tileSize is null after destroy" );
     }
+
+    function test_setOpacity(t) {
+
+        t.plan(5);
+
+        var map = new OpenLayers.Map('map');
+        var layer = new OpenLayers.Layer.WMS('', '', {}, {
+            isBaseLayer: true,
+            opacity: '0.6'
+        });
+        map.addLayer(layer);
+        // setCenter adds tiles to the layer's grid
+        map.setCenter(new OpenLayers.LonLat(0, 0), 5);
+
+        var tile = layer.grid[0][0], tileImg = tile.imgDiv;
+
+        tile.onImageLoad(); // simulate an image load event
+        t.eq(layer.opacity, '0.6', 'layer opacity value is correct');
+        t.eq(parseFloat(tileImg.style.opacity), 0.6, 'tile opacity is correct');
+
+        layer.setOpacity('0.2');
+        t.eq(layer.opacity, '0.2', 'layer opacity value is correct');
+        t.eq(parseFloat(tileImg.style.opacity), 0.2, 'tile opacity is correct');
+
+        tile = layer.addTile(new OpenLayers.Bounds(1, 2, 3, 4),
+                             new OpenLayers.Pixel(5, 6));
+        tile.draw(); // add tile to the grid
+        tile.onImageLoad(); // simulate an image load event
+        t.eq(parseFloat(tile.imgDiv.style.opacity), 0.2, "tile opacity is correc");
+
+        map.destroy();
+    }
     
     function test_getServerResolution(t) {
 
diff --git a/tests/Layer/MapServer.html b/tests/Layer/MapServer.html
index 11173cb14b..004731db49 100644
--- a/tests/Layer/MapServer.html
+++ b/tests/Layer/MapServer.html
@@ -190,31 +190,6 @@
 
     }
 
-    function test_Layer_MapServer_setOpacity (t) {
-        t.plan( 5 );
-
-        var map = new OpenLayers.Map('map');
-        map.projection = "xx";
-        tUrl = "http://labs.metacarta.com/cgi-bin/mapserv";
-        tParams = { layers: 'basic', 
-                   format: 'image/png'};
-        tOptions = { 'opacity': '0.5' };           
-        var tLayer = new OpenLayers.Layer.MapServer(name, tUrl, tParams, tOptions);
-        map.addLayer(tLayer);
-        map.zoomToMaxExtent();
-        t.eq(tLayer.opacity, "0.5", "Opacity is set correctly");
-        t.eq(parseFloat(tLayer.div.firstChild.style.opacity), 0.5, "Opacity on tile is correct");
-        tLayer.setOpacity("0.6");
-        t.eq(tLayer.opacity, "0.6", "setOpacity works properly");
-        t.eq(parseFloat(tLayer.div.firstChild.style.opacity), 0.6, "Opacity on tile is changed correctly");
-        var pixel = new OpenLayers.Pixel(5,6);
-        var tile = tLayer.addTile(new OpenLayers.Bounds(1,2,3,4), pixel);
-        tile.draw();
-        t.eq(parseFloat(tile.imgDiv.style.opacity), 0.6, "Tile opacity is set correctly");
-        map.destroy();
-
-    }    
-    
     function test_Layer_MapServer_singleTile (t) {
         t.plan( 5 );
         var map = new OpenLayers.Map('map');
diff --git a/tests/Layer/WMS.html b/tests/Layer/WMS.html
index f18a0d7598..757c6b92b2 100644
--- a/tests/Layer/WMS.html
+++ b/tests/Layer/WMS.html
@@ -271,38 +271,6 @@
 
     }
 
-    function test_Layer_WMS_setOpacity (t) {
-        t.plan( 5 );
-
-        var map = new OpenLayers.Map('map');
-        tUrl = "http://octo.metacarta.com/cgi-bin/mapserv";
-        tParams = { layers: 'basic',
-                   format: 'image/png'};
-        tOptions = { 'opacity': '0.5' };
-        var tLayer = new OpenLayers.Layer.WMS(name, tUrl, tParams, tOptions);
-        map.addLayer(tLayer);
-        map.setCenter(new OpenLayers.LonLat(0,0), 5);
-
-        var tile = tLayer.grid[0][0],
-            tileImg = tile.imgDiv;
-
-        t.eq(tLayer.opacity, "0.5", "Opacity is set correctly");
-        tile.onImageLoad(); // simulate a 'load' image event
-        t.eq(parseFloat(tileImg.style.opacity), 0.5, "Opacity on tile is correct");
-
-        tLayer.setOpacity("0.6");
-        t.eq(tLayer.opacity, "0.6", "setOpacity works properly");
-        t.eq(parseFloat(tileImg.style.opacity), 0.6, "Opacity on tile is changed correctly");
-
-        var pixel = new OpenLayers.Pixel(5,6);
-        var tile = tLayer.addTile(new OpenLayers.Bounds(1,2,3,4), pixel);
-        tile.draw();
-        tile.onImageLoad(); // simulate a 'load' image event
-        t.eq(parseFloat(tile.imgDiv.style.opacity), 0.6, "Tile opacity is set correctly");
-
-        map.destroy();
-    }
-
     function test_Layer_WMS_noGutters (t) {
         t.plan(2);
         var map = new OpenLayers.Map('map');