In many cases, not all of the test effort is carried out by a single test team, composed of fellow employees of the rest of the project team, at a single and same location as the rest of the project team. If the test effort occurs at multiple locations, that test effort may be called distributed. If the test effort is carried out at one or more locations by people who are not fellow employees of the rest of the project team and who are not co-located with the project team, that test effort may be called outsourced. If the test effort is carried out by people who are co-located with the project team but who are not fellow employees, that test effort may be called insourced.
Common across all such test efforts is the need for clear channels of communication and well-defined expectations for missions, tasks, and deliverables. The project team must rely less on informal communication channels like hallway conversations and colleagues spending social time together. Location, time-zone, cultural and language differences make these issues even more critical.
Also common across all such test efforts is the need for alignment of methodologies. If two test groups use different methodologies or the test group uses a different methodology than development or project management, that will result in significant problems, especially during test execution.
For distributed testing, the division of the test work across the multiple locations must be explicit and intelligently decided. Without such guidance, the most competent group may not do the test work they are highly qualified for. Furthermore, the test work as a whole will suffer from gaps (which increase residual quality risk on delivery) and overlap (which reduce efficiency).
Finally, for all such test efforts, it is critical that the entire project team develop and maintain trust that each of the test team(s) will carry out their roles properly in spite of organizational, cultural, language, and geographical boundaries. Lack of trust leads to inefficiencies and delays associated with verifying activities, apportioning blame for problems, and playing organizational politics.