Software Testing Life Cycle (STLC)
Software Testing Life Cycle (STLC) is a systematic sequence of activities performed during the testing process to ensure software quality. It defines what testing activities are performed, in what order, and with what deliverables.
STLC answers: “How is testing planned, executed, and closed?”
1. Definition
Software Testing Life Cycle (STLC) is a systematic sequence of activities performed during the testing process to ensure software quality. It defines what testing activities are performed, in what order, and with what deliverables.
2. Purpose of STLC
- Provide a structured testing approach
- Ensure complete test coverage
- Detect defects early and systematically
- Improve quality and predictability
- Support release decisions
3. Phases of STLC
3.1 Requirement Analysis
Activities
- Analyze requirements for testability
- Identify functional and non-functional test scenarios
- Clarify ambiguities with stakeholders
Deliverables
- Requirement review comments
- High-level test scenarios
3.2 Test Planning
Activities
- Define test strategy and scope
- Estimate testing effort
- Identify risks and mitigation
- Plan resources and schedule
Deliverables
- Test Plan
- Test Strategy
- Effort estimation
3.3 Test Case Design & Test Data Preparation
Activities
- Write detailed test cases
- Design negative and edge scenarios
- Prepare test data
Deliverables
- Test cases
- Test data
- RTM (Requirement Traceability Matrix)
3.4 Test Environment Setup
Activities
- Validate test environment readiness
- Ensure required configurations
- Verify access and data availability
Deliverables
- Environment readiness confirmation
3.5 Test Execution
Activities
- Execute test cases
- Log defects
- Perform re-testing and regression testing
- Update test status
Deliverables
- Executed test cases
- Defect reports
- Test execution reports
3.6 Test Closure
Activities
- Evaluate exit criteria
- Prepare test summary report
- Analyze defect trends
- Capture lessons learned
Deliverables
- Test Summary Report
- Test closure sign-off
4. Entry and Exit Criteria (STLC View)
Entry Criteria
- Approved requirements
- Test environment ready
- Test cases reviewed
Exit Criteria
- Test cases executed
- Critical defects closed
- Test coverage achieved
5. STLC vs SDLC
| Aspect | STLC | SDLC |
|---|---|---|
| Focus | Testing activities | Development activities |
| Scope | Quality validation | Product creation |
| Timeline | Within SDLC | Entire lifecycle |
6. Role of Manual Tester in STLC
- Participate early in requirement analysis
- Design effective test cases
- Execute tests with user mindset
- Report defects clearly
- Support release decisions
7. Real-Time Example
If environment setup is delayed:
- Test execution is blocked
- Schedule is impacted
- Defect detection is delayed
STLC helps identify and manage such risks early.
8. Common Mistakes
- Skipping requirement analysis
- Poor test planning
- Incomplete test data
- Ignoring test closure activities
9. Interview-Ready Answers
Short answer:
STLC defines the sequence of testing activities from requirement analysis to test closure to ensure software quality.
Detailed answer:
STLC is a structured testing process that outlines planning, designing, executing, and closing testing activities to deliver a quality software product.
10. Key Takeaway
STLC ensures testing is planned, controlled, and measurable, not random.