[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/SubPlotSpec.js

@@ -135,6 +135,22 @@ define(
                     ]
                 );
             });
+
+            it("provides access to a drawable object", function () {
+                expect(typeof subplot.getDrawingObject()).toEqual('object');
+            });
+
+            it("allows a domain offset to be provided", function () {
+                // Domain object is needed to adjust canvas coordinates
+                // to avoid loss-of-precision associated with converting
+                // to 32 bit floats.
+                subplot.setDomainOffset(3);
+                subplot.update();
+                // Should have adjusted the origin accordingly
+                expect(subplot.getDrawingObject().origin[0])
+                    .toEqual(2);
+            });
+
         });
     }
 );

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();
+            });
+
         });
     }
 );