Trying to improve coverage in tests.

Still lots of implicit any catching me.  Having to be explicit in the
test.

chartist/chartist-tests.ts

@@ -14,7 +14,7 @@ new Chartist.Line('.ct-chart', {
   }
 });
 
-var chart = new Chartist.Line('.ct-chart', {
+var lineChart = new Chartist.Line('.ct-chart', {
   labels: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16],
   series: [
     [5, 5, 10, 8, 7, 5, 4, null, null, null, 10, 10, 7, 8, 6, 9],
@@ -43,8 +43,6 @@ new Chartist.Line('.ct-chart', {
   ]
 });
 
-
-
 var data = {
   series: [5, 3, 4]
 };
@@ -66,3 +64,53 @@ new Chartist.Pie('.ct-chart', {
   total: 200,
   showLabel: false
 });
+
+
+// Animation Donut example
+
+var chart = new Chartist.Pie('.ct-chart', {
+  series: [10, 20, 50, 20, 5, 50, 15],
+  labels: [1, 2, 3, 4, 5, 6, 7]
+}, {
+  donut: true,
+  showLabel: false
+});
+
+chart.on('draw', function(data: any) {
+  if(data.type === 'slice') {
+    // Get the total path length in order to use for dash array animation
+    var pathLength = data.element._node.getTotalLength();
+
+    // Set a dasharray that matches the path length as prerequisite to animate dashoffset
+    data.element.attr({
+      'stroke-dasharray': pathLength + 'px ' + pathLength + 'px'
+    });
+
+    // Create animation definition while also assigning an ID to the animation for later sync usage
+    var animationDefinition: any = {
+      'stroke-dashoffset': {
+        id: 'anim' + data.index,
+        dur: 1000,
+        from: -pathLength + 'px',
+        to:  '0px',
+        easing: Chartist.Svg.Easing.easeOutQuint,
+        // We need to use `fill: 'freeze'` otherwise our animation will fall back to initial (not visible)
+        fill: 'freeze'
+      }
+    };
+
+    // If this was not the first slice, we need to time the animation so that it uses the end sync event of the previous animation
+    if(data.index !== 0) {
+      animationDefinition['stroke-dashoffset'].begin = 'anim' + (data.index - 1) + '.end';
+    }
+
+    // We need to set an initial value before the animation starts as we are not in guided mode which would do that for us
+    data.element.attr({
+      'stroke-dashoffset': -pathLength + 'px'
+    });
+
+    // We can't use guided mode as the animations need to rely on setting begin manually
+    // See http://gionkunz.github.io/chartist-js/api-documentation.html#chartistsvg-function-animate
+    data.element.animate(animationDefinition, false);
+  }
+});