There are a number of files that are only loaded when another function is called (for example, load a reporting class when displaying a widget). An autoloader would be the ideal way to handle this (both in production and for tests), but until PHP compatibility is sorted out this commit adds an easy fix:
Testcases can now populate the protected, static $includes property with filepaths relative to the project root; when the testcase boots up, these files will automatically be included.
Steve Grunwell