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Waterfall Model - QA Role and Entry/Exit Criteria
The Waterfall model is the original structured SDLC - a linear, sequential process where each phase completes fully before the next begins. While largely replaced by Agile in product companies, Waterfall is still widely used in government contracts, regulated industries (medical devices, financial systems), and large enterprise projects where requirements are stable and changes are expensive. QA engineers working in Waterfall environments need to understand the specific demands this model places on testing.
QA in the Waterfall Model
- Requirements Phase: QA engineers review requirements documents for clarity, completeness, and testability. This is the highest-ROI QA activity in Waterfall - requirements defects here are 100x cheaper to fix than in production
- Design Phase: QA reviews system design documents, database schemas, and API specifications. They begin drafting the Master Test Plan during this phase - not waiting for code
- Development Phase: While code is written, QA prepares detailed test cases, configures test environments, and prepares test data. No idle waiting - parallel preparation is essential
- Testing Phase: Formal System Testing, Integration Testing, and UAT. Waterfall dedicates a specific time-boxed phase to testing. Entry criteria: all planned code delivered; exit criteria: all critical defects fixed, defined test coverage achieved
- Deployment/Maintenance: Production deployment with QA smoke testing, then ongoing regression as fixes are applied
Entry and Exit Criteria in Waterfall
Entry criteria define when a phase can BEGIN - the conditions that must be met. Exit criteria define when a phase can END - the conditions that must be achieved to move forward. Example Testing Phase entry criteria: all code modules delivered, unit test reports reviewed, test environment configured, test data prepared. Example Testing Phase exit criteria: 95% of test cases executed, zero critical defects open, all high-priority defects fixed and regression tested, Test Summary Report signed off. These formal gates prevent the classic Waterfall failure: testing starting too late because development ran over, leading to a compressed test phase with critical defects shipped to production. QA engineers define and enforce these criteria - they are quality gates, not bureaucracy.
Quality assurance follows a structured testing lifecycle
Tip
Tip
Practice Waterfall Model QA Role and EntryExit Criteria in small, isolated examples before integrating into larger projects. Breaking concepts into small experiments builds genuine understanding faster than reading alone.
Practice Task
Note
Practice Task - (1) Write a working example of Waterfall Model QA Role and EntryExit Criteria from scratch without looking at notes. (2) Modify it to handle an edge case (empty input, null value, or error state). (3) Share your solution in the Priygop community for feedback.
Quick Quiz
Common Mistake
Warning
A common mistake with Waterfall Model QA Role and EntryExit Criteria is skipping edge case testing - empty inputs, null values, and unexpected data types. Always validate boundary conditions to write robust, production-ready qa engineering code.
Key Takeaways
- The Waterfall model is the original structured SDLC - a linear, sequential process where each phase completes fully before the next begins.
- Requirements Phase: QA engineers review requirements documents for clarity, completeness, and testability. This is the highest-ROI QA activity in Waterfall - requirements defects here are 100x cheaper to fix than in production
- Design Phase: QA reviews system design documents, database schemas, and API specifications. They begin drafting the Master Test Plan during this phase - not waiting for code
- Development Phase: While code is written, QA prepares detailed test cases, configures test environments, and prepares test data. No idle waiting - parallel preparation is essential