Update unit test to increase coverage:

+--------------------------------------+-----------+-----------+-----------+-----------+
| File                                 |   % Stmts |% Branches |   % Funcs |   % Lines |
+--------------------------------------+-----------+-----------+-----------+-----------+
| gallery-charts-stockindicators/      |     83.07 |     58.58 |     89.44 |     83.07 |
|    gallery-charts-stockindicators.js |     83.07 |     58.58 |     89.44 |     83.07 |
+--------------------------------------+-----------+-----------+-----------+-----------+
| All files                            |     83.07 |     58.58 |     89.44 |     83.07 |
+--------------------------------------+-----------+-----------+-----------+-----------+

	modified:   tests/unit/assets/column-volume-tests.js
	modified:   tests/unit/charts-stockindicators.html
	modified:   tests/unit/column-volume.html
Forgot asset file for tests.