Added unit test for color stretch filter

test/unit/filters/ColorStretch-test.js

@@ -0,0 +1,49 @@
+suite('Color Stretch', function () {
+    // ======================================================
+    test('Enhancing Colors', function (done) {
+        var stage = addStage();
+
+        var shapesLayer = new Kinetic.Layer();
+
+        // The important line!
+        shapesLayer.on('draw', function () {
+          var imageData = this.getContext().getImageData(0, 0, this.getCanvas().width, this.getCanvas().height);
+          var scratchData = this.getContext().createImageData(imageData); // only size copied
+          Kinetic.Filters.ColorStretch(imageData, scratchData, {});
+          this.getContext().putImageData(scratchData, 0, 0);
+        });
+
+        var triangle = new Kinetic.RegularPolygon({
+          x: stage.getWidth() / 4,
+          y: stage.getHeight() / 2,
+          sides: 3,
+          radius: 80,
+          fillRadialGradientStartPoint: 0,
+          fillRadialGradientStartRadius: 0,
+          fillRadialGradientEndPoint: 0,
+          fillRadialGradientEndRadius: 70,
+          fillRadialGradientColorStops: [0, '#881111', 0.5, '#888811', 1, '#000088'],
+          stroke: 'black',
+          strokeWidth: 4,
+          draggable: true
+        });
+
+        var circle = new Kinetic.Circle({
+          x: 3 * stage.getWidth() / 4,
+          y: stage.getHeight() / 2,
+          radius: 70,
+          fill: '#880000',
+          stroke: 'black',
+          strokeWidth: 4,
+          draggable: true,
+          id: 'myCircle'
+        });
+
+        shapesLayer.add(circle);
+        shapesLayer.add(triangle);
+
+        stage.add(shapesLayer);
+
+        done();
+    });
+});