better capable konva context with native context

test/unit/Context-test.js

@@ -0,0 +1,54 @@
+suite('Context', function() {
+    // ======================================================
+    var contextMethods = ['clearRect', 'fillRect', 'strokeRect',
+        'fillText', 'strokeText', 'measureText', 'getLineDash', 'setLineDash',
+        'createLinearGradient', 'createRadialGradient', 'createPattern',
+        'beginPath', 'closePath', 'moveTo', 'lineTo', 'bezierCurveTo', 'quadraticCurveTo',
+        'arc', 'arcTo', 'rect', 'fill', 'stroke', 'clip', 'isPointInPath',
+        'scale', 'rotate', 'translate', 'transform', 'setTransform', 'drawImage',
+        'createImageData', 'getImageData', 'putImageData', 'save', 'restore'];
+
+    var contextProperties = ['fillStyle', 'strokeStyle', 'shadowColor', 'shadowBlur', 'shadowOffsetX',
+        'shadowOffsetY', 'lineCap', 'lineJoin', 'lineWidth', 'miterLimit', 'font', 'textAlign', 'textBaseline',
+        'globalAlpha', 'globalCompositeOperation'];
+
+    test('context wrapper should work like native context', function() {
+        var stage = addStage();
+
+        var layer = new Konva.Layer();
+
+        var circle = new Konva.Circle({
+            x: 100,
+            y: 70,
+            radius: 70,
+            fill: 'green',
+            stroke: 'blue',
+            strokeWidth: 4,
+            draggable : true
+        });
+
+        layer.add(circle);
+        stage.add(layer);
+
+        var context = layer.getContext();
+        var nativeContext = context._context;
+
+        contextMethods.forEach(function(method) {
+            assert.equal(typeof nativeContext[method], 'function', 'native context has no method ' + method);
+            assert.equal(typeof context[method], 'function', 'context wrapper has no method ' + method);
+        });
+
+        contextProperties.forEach(function(prop) {
+            assert.equal(nativeContext.hasOwnProperty(prop), true, 'native context has no property ' + prop);
+            assert.equal(context[prop] !== undefined, true, 'context wrapper has no property ' + prop);
+        });
+
+        // test get
+        nativeContext.fillStyle = '#ff0000';
+        assert.equal(context.fillStyle, '#ff0000');
+
+        // test set
+        context.globalAlpha = 0.5;
+        assert.equal(context.globalAlpha, 0.5);
+    });
+});