Following Mahmoud et al., the Unit Testing phase comes before Implementation
because if non-conformance with the requirements is encountered here, less
energy is consumed if the process steps back to the Requirements phase than if
Unit Testing comes after the Implementation. However, this does not mean that
Unit Tests during the Implementation phase are not allowed. After Implementation
and System Testing, the Green Analysis phase is performed. This phase determines
the greenness of each increment by applying specific metrics to the
developed code.