[Plot] Begin separating out plot line handling

Begin separating out plot line buffer from the rest of plot;
managing this buffer separately will aid in merging realtime
and hsitorical data, WTD-806.

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

@@ -0,0 +1,72 @@
+/*global define,Promise,describe,it,expect,beforeEach,waitsFor,jasmine*/
+
+/**
+ * MergeModelsSpec. Created by vwoeltje on 11/6/14.
+ */
+define(
+    ["../../src/elements/PlotLineBuffer"],
+    function (PlotLineBuffer) {
+        "use strict";
+
+        var TEST_INITIAL_SIZE = 10,
+            TEST_MAX_SIZE = 40,
+            TEST_DOMAIN_OFFSET = 42;
+
+        describe("A plot line buffer", function () {
+            var mockSeries,
+                testDomainValues,
+                testRangeValues,
+                buffer;
+
+            beforeEach(function () {
+                testDomainValues = [ 1, 3, 7, 9, 14, 15 ];
+                testRangeValues = [ 8, 0, 3, 9, 8, 11 ];
+                mockSeries = jasmine.createSpyObj(
+                    "series",
+                    ['getPointCount', 'getDomainValue', 'getRangeValue']
+                );
+                mockSeries.getPointCount.andCallFake(function () {
+                    return testDomainValues.length;
+                });
+                mockSeries.getDomainValue.andCallFake(function (i) {
+                    return testDomainValues[i];
+                });
+                mockSeries.getRangeValue.andCallFake(function (i) {
+                    return testRangeValues[i];
+                });
+
+                buffer = new PlotLineBuffer(
+                    TEST_DOMAIN_OFFSET,
+                    TEST_INITIAL_SIZE,
+                    TEST_MAX_SIZE
+                );
+
+                // Start with some data in there
+                buffer.insert(mockSeries, 0);
+            });
+
+            it("allows insertion of series data", function () {
+                // Convert to a regular array for checking.
+                // Verify that domain/ranges were interleaved and
+                // that domain offset was adjusted for.
+                expect(
+                    Array.prototype.slice.call(buffer.getBuffer()).slice(0, 12)
+                ).toEqual([ -41, 8, -39, 0, -35, 3, -33, 9, -28, 8, -27, 11]);
+            });
+
+            it("finds insertion indexes", function () {
+                expect(buffer.findInsertionIndex(0)).toEqual(0);
+                expect(buffer.findInsertionIndex(2)).toEqual(1);
+                expect(buffer.findInsertionIndex(5)).toEqual(2);
+                expect(buffer.findInsertionIndex(10)).toEqual(4);
+                expect(buffer.findInsertionIndex(14.5)).toEqual(5);
+                expect(buffer.findInsertionIndex(20)).toEqual(6);
+
+                // 9 is already in there, disallow insertion
+                expect(buffer.findInsertionIndex(9)).toEqual(-1);
+            });
+
+
+        });
+    }
+);