The testing strategy for the payroll system involves rigorous testing at four levels – unit testing, integration testing, system testing, and user acceptance testing.
Unit Testing: All individual modules and program units that make up the payroll application will undergo unit testing. This includes functions, classes, databases, APIs etc. Unit tests will cover both normal and edge conditions to test validity, functionality and accuracy. We will use a test-driven development approach and implement unit tests even as the code is being written to ensure code quality. A code coverage target of 80% will be set to ensure that most of the code paths are validated through unit testing.
Integration Testing: Once the individual units have undergone unit testing and bugs fixed, integration testing will involve testing how different system modules interact with each other. Tests will validate the interface behavior between different components like the UI layer, business logic layer, and database layer. Error handling, parameter passing and flow of control between modules will be rigorously tested. A modular integration testing approach will be followed where integration of small subsets is tested iteratively to catch issues early.
System Testing: On obtaining satisfactory results from unit and integration testing, system testing will validate the overall system functionality as a whole. End-to-end scenarios mimicking real user flows will be designed and tested to check requirements implementation. Performance and load testing will also be conducted at this stage to test response times and check system behavior under load conditions. Security tests like penetration testing will be carried out by external auditors to identify vulnerabilities.
User Acceptance Testing: The final stage of testing prior to deployment will involve exhaustive user acceptance testing (UAT) by the client users themselves. A dedicated UAT environment exactly mirroring production will be set up for testing. Users will validate pay runs, generate payslips and reports, configure rules and thresholds through testing. They will also provide sign off on acceptance criteria and report any bugs found for fixing. Only after clearing UAT, the system will be considered ready for deployment to production.
A multi-phase phased deployment strategy will be followed to minimize risks during implementation. The key steps are:
Development and Staging Environments: Development of new features and testing will happen in initial environments isolated from production. Rigorous regression testing will happen across environments after each deployment.
Pilot deployment: After UAT sign off, the system will first be deployed to a select pilot user group and select location/department. Their usage and feedback will be monitored closely before proceeding to next phase.
Phase-wise rollout: Subsequent deployments will happen in phases with rollout to different company locations/departments. Each phase will involve monitoring and stabilization before moving to next phase. This reduces load and ensures steady-state operation.
Fallback strategy: A fallback strategy involving capability to roll back to previous version will be in place. Database scripts will allow reverting schema and data changes. Standby previous version will also be available in case required.
Monitoring and Support: Dedicated support and monitoring will be provided post deployment. An incident and problem management process will be followed. Product support will collect logs, diagnose and resolve issues. Periodic reviews will analyze system health and user experience.
Continuous Improvement: Feedback and incident resolutions will be used for further improvements to software, deployment process and support approach on an ongoing basis. Additional features and capabilities can also be launched periodically following the same phased approach.
Regular audits will also be performed to assess compliance with processes, security controls and regulatory guidelines after deployment into production. This detailed testing and phased deployment strategy aims to deliver a robust and reliable payroll system satisfying business and user requirements.