The TMMi model (see figure below) looks at software testing at different maturity levels, with the assumption that all organizations start at TMMi level 1 of the maturity ladder. The more mature an organizations' testing practices, the higher level of TMMi maturity the organization fullfils.
The model has a staged architecture for test process improvement. It contains levels through which an organization passes as its testing process evolves from one that is ad hoc and unmanaged, to one that is managed, defined, measured, and in optimization mode, see figure 1 below. Achieving each level ensures that an adequate improvement has been laid as a foundation for the next stage.
Test process improvement efforts are focused on the needs of the organization in the context of its business environment. Moving through the different maturity levels increases the capability of test and software quality management to align with the needs of the business. The benefits being among others improved software product quality with fewer defects, but also improved test efficiency.
The scope for each of the different maturity levels are as follows:
Level 2 – Managed
Where the fundamental test approach is established and managed, which may vary from project to project within an organization with test policy and strategy being a focus area. This provides direction for planning monitoring and control, test design techniques with each project having control over test execution. At level 2 test environments are also in place for projects.
Level 3 – Defined
Establishes that all projects are following the same standards and procedures throughout the organizations or organizational unit. Level 2 is still being done, and teams are now organized, test training programs exist, test is integrated into the development life cycle and integrated into all projects from early in development. Non-functional testing is planned and executed in all projects and reviews are used in each project as well.
Level 4 – Measured
Measurement of activities and outcomes are thoroughly applied early in all projects to establish at each stage of development the projects are as defect free as possible. Advanced reviews are in use throughout all projects building on the review practices introduced at 3.
Level 5 – Optimization
At this level all activities and outcomes are assessed and optimize activities are in place to ensure continuous improvement toward defect prevention and optimized quality.