Add test for Worker + Offscreen canvas

Author: sandeepmistry

test/all.html

@@ -43,6 +43,8 @@
   <script src="features/read-color-texture.js"></script>
   <script src="features/read-from-texture.js"></script>
   <script src="features/sum-ab.js"></script>
+  <script src="features/float-output.js"></script>
+  <script src="features/offscreen-canvas.js"></script>
 
   <!-- internal -->
   <script src="internal/context-inheritance.js"></script>

test/features/offscreen-canvas.js

@@ -0,0 +1,35 @@
+(function() {
+  if (typeof(document) === 'undefined') {
+    // inside Worker
+    window = {};
+    importScripts('../../bin/gpu.js');
+
+    onmessage = function(e) {
+      const gpu = new window.GPU();
+
+      postMessage(gpu.getMode());
+    };
+
+    return;
+  }
+
+  // skip test if browser doesn't support Workers or OffscreenCanvas
+  var test = (typeof(Worker) === 'undefined') || (typeof(OffscreenCanvas) === 'undefined') ?
+              QUnit.skip : QUnit.test;
+
+  test( 'OffscreenCanvas used in Worker', function(assert) {
+    var worker = new Worker('features/offscreen-canvas.js');
+    var done = assert.async();
+
+    worker.onmessage = function(e) {
+      var mode = e.data;
+
+      assert.equal( mode, 'gpu', 'GPU mode used in Worker' );
+
+      done();
+    };
+
+    worker.postMessage('test');
+  });
+
+})();