STLC in Software Testing

Introduction

When learning about software testing, one of the key concepts you’ll come across is STLC in software testing. STLC stands for Software Testing Life Cycle, and it refers to the structured sequence of activities that guide the testing process. Just like SDLC (Software Development Life Cycle) defines how software is built, STLC defines how software is tested.

In this post, we’ll break down what STLC is, why it matters, and walk through each phase step by step.

What is STLC in Software Testing?

STLC in software testing is a set of phases that testers follow to ensure the quality of a software product. It begins when requirements are defined and continues until the software is released. Each phase has specific entry and exit criteria, deliverables, and objectives.

Simply put: STLC is the roadmap for testing activities.

Why is STLC Important?

• Structured process – prevents missed steps and ensures consistency.
• Better coverage – every requirement is validated against tests.
• Early detection of defects – issues are caught before release.
• Improved collaboration – testers, developers, and stakeholders stay aligned.

Phases of STLC in Software Testing

1. Requirement Analysis

• Test team studies requirements (functional & non-functional).
• Identify testable requirements.
• Risks and ambiguities are discussed with stakeholders.

Deliverables: Requirement traceability matrix (RTM), list of open questions.

2. Test Planning

• Define scope, objectives, and test strategy.
• Estimate effort and resources needed.
• Identify tools (manual/automation).
• Define risks and mitigation strategies.

Deliverables: Test plan document, resource allocation plan.

3. Test Case Development

• Write detailed test cases and prepare test data.
• Peer reviews ensure quality and coverage.
• Automation scripts may be developed in parallel.

Deliverables: Test cases, test scripts, test data.

4. Test Environment Setup

• Install necessary hardware, software, and tools.
• Configure environments (staging, QA, UAT).
• Sometimes runs parallel with test case development.

Deliverables: Test environment readiness report.

5. Test Execution

• Execute test cases in the prepared environment.
• Compare expected results with actual results.
• Log defects if outcomes don’t match expectations.

Deliverables: Test execution report, defect reports.

6. Test Cycle Closure

• Evaluate test completion against exit criteria.
• Prepare final test summary report.
• Lessons learned are documented for future projects.

Deliverables: Test summary report, closure report, metrics.

Difference Between STLC and SDLC

• SDLC (Software Development Life Cycle)

  • Focuses on development of software
  • Starts with requirement gathering and ends with deployment
  • Activities performed by developers
  • Produces working software

• STLC (Software Testing Life Cycle)

  • Focuses on testing of software
  • Starts with requirement analysis and ends with test closure
  • Activities performed by testers
  • Produces quality assurance and validation

Example in Real Projects

Imagine building a mobile banking app.

• Requirement analysis → testers ensure login, transfer, and balance check are testable.
• Test planning → strategy for manual & automation tests.
• Test case development → scenarios like “transfer money with insufficient balance.”
• Execution → run these cases in QA environment, report bugs, and retest fixes.

This structured approach ensures the app is reliable and secure before reaching users.

Conclusion

STLC in software testing is more than just a set of steps—it’s a disciplined approach that ensures software meets quality standards before release. By following the phases of STLC, teams can minimize risks, catch defects early, and deliver a better user experience.

If you’re preparing for a software testing interview, understanding STLC in software testing is crucial. It’s one of the most common questions and a must-know concept for both beginners and experienced testers.

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Related reading:

• What Is Software Testing? Beginner Guide
• Defect Life Cycle Explained
• Exploratory Testing for Beginners
• How to Write Test Cases That Don’t Suck