Added test for compiling showOn

tether-shepherd/tether-shepherd-tests.ts

@@ -46,6 +46,9 @@ var step2Options: TetherShepherd.IShepherdTourStepOptions = {
         destroy: () => {
             console.log('Destroyed the Step 2');
         }
+    },
+    showOn: () => {
+        return true;
     }
 };
 
@@ -55,4 +58,4 @@ var queriedStep = tour.getById('test-step-2');
 
 queriedStep.destroy();
 
-tour.start();
+tour.start();