Add rendering test

test/rendering/cases/layer-tile-stack-opacity/main.js

@@ -0,0 +1,47 @@
+import Map from '../../../../src/ol/Map.js';
+import TileLayer from '../../../../src/ol/layer/Tile.js';
+import View from '../../../../src/ol/View.js';
+import XYZ from '../../../../src/ol/source/XYZ.js';
+import {fromLonLat} from '../../../../src/ol/proj.js';
+
+const center = fromLonLat([-80.4, 32.49]);
+
+const layer1 = new TileLayer({
+  source: new XYZ({
+    url: '/data/tiles/south-carolina/{z}/{x}/1-{y}.png',
+    transition: 0,
+  }),
+});
+const layer2 = new TileLayer({
+  source: new XYZ({
+    url: '/data/tiles/south-carolina/{z}/{x}/2-{y}.png',
+    transition: 0,
+  }),
+  opacity: 0.5,
+});
+const layer3 = new TileLayer({
+  source: new XYZ({
+    url: '/data/tiles/south-carolina/{z}/{x}/3-{y}.png',
+    transition: 0,
+  }),
+  opacity: 0.5,
+});
+const layer4 = new TileLayer({
+  source: new XYZ({
+    url: '/data/tiles/south-carolina/{z}/{x}/4-{y}.png',
+    transition: 0,
+  }),
+  opacity: 0.5,
+});
+
+new Map({
+  pixelRatio: 1,
+  layers: [layer1, layer2, layer3, layer4],
+  target: 'map',
+  view: new View({
+    center: center,
+    zoom: 11.4,
+  }),
+});
+
+render();