[Plot] Update specs

Update specs with minor changes related to using
telemetrySubscriber to populate plot with streaming
data, WTD-751 and WTD-784.

platform/features/plot/test/elements/PlotPreparerSpec.js

@@ -1,4 +1,4 @@
-/*global define,Promise,describe,it,expect,beforeEach,waitsFor,jasmine*/
+/*global define,Promise,describe,it,expect,beforeEach,waitsFor,jasmine,Float32Array*/
 
 /**
  * MergeModelsSpec. Created by vwoeltje on 11/6/14.
@@ -60,6 +60,13 @@ define(
                 expect(preparer.getDimensions[1]).not.toEqual(0);
             });
 
+            it("provides buffers", function () {
+                var datas = [makeMockData(0)],
+                    preparer = new PlotPreparer(datas);
+                expect(preparer.getBuffers()[0] instanceof Float32Array)
+                    .toBeTruthy();
+            });
+
         });
     }
 );