One of the biggest mistakes in any project is to keep testers away till late stages of the development. One reason for this is the way people look to testing. Actually, testing is a constructive activity and not a destructive one as many think. This can be seen obviously by looking to the goals of testing which are to provide objective input to facilitate business decisions and to keep stakeholders aware of all issues or concerns that relate to shipping a product*.
Testers role is growing and no longer limited to finding issues only. The role of testing starts directly from the requirements stage of the project. Testers can also have a beneficial contribution in the design stage and coding where they can sit with the programmers to help them ensure the quality of their work.
Testers can also help customers know what they really want. This gives an advantage of clearer requirements to be delivered to development team. Also, ensuring that features are developed as per customer expectations. This is done also through the collaboration between testers, project manager and the development team in order to get the job done in the right way.
Finally, one of the advantages of such involvement is reduction of cost, time and effort of finding and fixing issues in the project. The later the issues are found in project phases the higher cost, time and effort to fix them.
* Purpose of testing – Robert Sabourin