Test Plan is the scheduler for entire Testing process. The 
Test Plan describes the approach to all development, unit, 
integration, system, qualification and acceptance testing 
needed to complete a project properly. 

Establishing a test plan based on business requirements and 
design specification is essential for the successful 
acceptance of a project's deliverables. It is important to 
note that the higher risk a project has, the greater the 
need for a commensurate amount of testing. The project 
Schedule & Task Plan and the project Staffing Plan need to 
account for testing requirements during the planning and 
execution phases of the project. 

Testing validates the requirements defined for the projects 
objectives and deliverables. Though IT project practices 
require testing throughout the execution phase of a 
project, undoubtedly the most important testing occurs at 
the end of development and prior to deployment. Orderly 
test plans that specify the criteria for test passage or 
failure are critical to a project's success.