STLC – Software Testing Life Cycle

STLC | Software Testing Life Cycle

Last updated on

Software Testing Life Cycle, often abbreviated as STLC, is an indispensable aspect of the software development life cycle (SDLC). This tutorial will help you learn more about it, its phases, advantages, and disadvantages. 

As customers, we always enjoy using high-performance, error-free software products. We give the utmost importance to the functionality and quality of products. But how do software development organizations validate the quality and correctness of software solutions? This is where software testing comes into play. 

Testing was considered a single-phase activity in the early days of software development. It was performed only after the coding or the implementation phase. 

But after the evolution of the development process and with the increasing complexity of software applications, the testing activities started becoming more complex and standardized, ensuring the effectiveness of applications under test. This led to the Software Testing Life Cycle or STLC. 

In this tutorial, we will study STLC, its various phases, and its advantages & disadvantages.

So, let us begin!

What is STLC?

Software Testing Life Cycle or STLC refers to a series of systematic and well-defined steps performed while testing a software application to ensure it meets the specified requirements and is free from bugs.

In other words, it is a well-structured process containing a series of sequential phases, with each phase having its own deliverables and objectives. This process results in the delivery of top-quality, reliable, and fully-functional software products. 

The primary goal of STLC is to detect or uncover all possible bugs and errors in a software product in the early stages of software development. It involves thorough testing of a product, identifying bugs, and getting them fixed before releasing the product to the market. 

In a nutshell, STLC is a comprehensive process to ensure the quality and functionality of software products. It assists organizations in delivering solutions that meet their requirements and expectations.


  • Concentrates only on testing software solutions. 
  • A child process of SDLC. 
  • Commences immediately after the requirements are defined. 
  • Understands the requirements and ensures a software product functions as expected. 
  • Identifies all possible bugs and reports them to the development team for fixing.

Phases of STLC

To ensure the production of a reliable product, testing every component or module is essential. If an organization falls short in the testing process, several complexities may arise after the software product launch in the market. As a result, testing a product thoroughly is necessary for the development process. 

Now, let’s see the well-defined phases of the software testing life cycle (STLC) and their goals and deliverables.

STLC Phases

1. Requirement Analysis

It is the first phase of STLC. It involves the testing team understanding and analyzing all requirements specified by stakeholders and end users. Testing professionals determine whether the requirements are testable or not. If any requirements are ambiguous, missing, or not testable, they communicate the same to stakeholders.

Activities Performed

  • Reviewing software requirements and all other documents. 
  • Identifying unclear and ambiguous requirements and missing requirements.  
  • Communicating with stakeholders in case of any unclear requirements. 
  • Uncovering potential risks in the testing process. 


Entry Criteria 

  • Requirements document containing both functional and non-functional requirements. 
  • Application design document. 
  • User acceptance criteria document.

Exit Criteria

  • Signed off RTM 
  • Signed off automation feasibility report from clients. 

The primary goal of this phase is that the testing team should clearly understand requirements and identify potential risks in the testing process. 

2. Test Planning and Control

Test planning is one of the most important activities in the test process. It involves defining all testing plans to meet the project requirements. The quality Analyst (QA) manager outlines the test plan strategy with the estimated cost and efforts for the project. 

At the same time, test control includes continuous monitoring of test progress with the set plan and escalating any deviation to the concerned stakeholders.


  • Determining testing objectives and scope. 
  • Creating a test strategy, which includes determining testing techniques and methods. 
  • Identifying the test environment, test cases, test data, and other resources. 
  • Estimating the required time and cost for testing. 
  • Delegating roles and responsibilities to the testing team. 
  • Reviewing and approving the test plan. 


  • Test plan document. 
  • Effort estimation document. 

Entry Criteria 

  • Requirements documents. 
  • Requirements traceability matrix (RTM). 
  • Test automation feasibility document. 

Exit Criteria 

  • Approved test plan strategy. 
  • Signed off effort estimation document. 

In the end, the testing team should have a comprehensive testing plan containing testing activities with defined deliverables and objectives.  

3. Test Case Development

This phase involves the actual test case creation. It also involves test data specification and automated test script creation using different automation tools like Selenium WebDriver, Katalon Studio, etc.


  • Creating clear and concise test cases and automation scripts. 
  • Reviewing and validating test cases. 
  • Creating test data and test scenarios. 
  • Determining the expected results for test cases. 
  • Mapping requirements to test cases in the requirement traceability matrix (RTM). 


  • Test cases and automation scripts. 
  • Test data. 

Entry Criteria 

  • Requirements document. 
  • RTM and test plan. 
  • Automation analysis report. 

Exit Criteria 

  • Reviewed and signed off test cases and automation scripts. 
  • Reviewed and signed off test data. 

At the end of this phase, the testing team has a comprehensive set of test cases providing the coverage of the application under test. This ensures a thorough testing process and uncovers and addresses potential issues before the software release. 

4. Test Environment Setup

This phase involves setting up a test environment closely simulating the real world. The testing team uses this environment to test the whole application. This phase does not involve the testing team and is carried out in parallel with the test case development phase. The test environment is created by developers or the customer. 

The different types of testing – manual, automated, performance, etc., are carried out here. 


  • Understand the architecture of the test environment and create a list of the required hardware and software requirements. 
  • Set up the test environment and test data. 
  • Carry out a smoke test on the build.


  • A ready environment with test data. 
  • The results of the smoke test. 

Entry Criteria 

  • System design and architecture documents. 
  • Environment set-up plan. 

Exit Criteria 

  • Complete test data setup. 
  • Successful smoke test. 
  • A working environment set up as per the defined criteria. 

5. Test Execution

This phase involves manual and automated test case execution. A team of testers tests the software build depending on the prepared test plans and test cases. During test case execution, any deviation from the expected result leads to the creation of defects in a defect management tool or the manual logging of bugs in an Excel sheet. Once the development team fixes the bugs, the QA team retests the bugs for validation.


  • Test Execution: Running test cases and scripts against the software application to uncover any bugs or issues. 
  • Defect Logging: Logging defects or issues found during testing in a defect tracking system with their details, such as severity, priority, and description. 
  • Test Result Analysis: Analyzing the results of test execution to determine the application’s performance and detects issues and errors. 
  • Defect Retesting: Retesting the application to address the defects found during test execution. 
  • Test Reporting: Documenting and reporting test results to stakeholders. 


  • Completed RTM with the status of test cases. 
  • Test cases with results. 
  • Defect reports. 

Entry Criteria 

  • RTM, test plan, and test scripts are available. 
  • A ready test environment. 
  • A ready set up of test data.  

Exit Criteria 

  • All planned tests are executed. 
  • All defects logged. 

The text execution process is iterative and repeated until the software application is free from bugs and ready to launch. 

6. Test Closure

This phase marks the formal closure of testing. It involves several activities, such as checking if all the project deliverables are delivered, archiving the test plan, test cases, automation scripts, and test environment, and documenting the learning. 

The testing team together discusses and analyzes testing artifacts and documents all strategies implemented during the testing process. Doing this helps the testing team to eliminate process bottlenecks in the future.


  • Test Summary Report: Creating a summary of all activities performed in the testing process. 
  • Test Environment Clean-up: Achieving all test data and artifacts and cleaning the test environment. 
  • Test Closure Report: Creating a report documenting all testing-related activities. 
  • Knowledge Transfer: Sharing of knowledge regarding the testing process among the team members. 
  • Feedback and Improvements: Collecting feedback from the testing process and using it as a reference for the future. 


  • Test closure report.

Entry Criteria 

  • Completed testing. 
  • Test results should be available. 
  • Defects logs should be available. 

Exit Criteria 

  • Test closure report signed off by clients. 

The test closure process involves documenting everything about the testing process and sharing lessons captured. 

Advantages of STLC

Here are some remarkable advantages of STLC: 

  • The testing team gets involved right from the initial phases of SDLC. This helps in a better understanding of the application, which results in overall better testing.
  • It improves the quality of each SDLC phase and also adds to the transparency of each process.
  • STLC ensures lesser project cost and timely delivery since the testing team can uncover bugs and anomalies quickly by following the systematic test process.
  • Since each STLC phase has a well-defined goal and deliverable so it helps in measuring the progress with the different milestones achieved in each phase.

Also, check the Difference between SDLC and STLC


That’s all about the software testing life cycle (STLC). It is a systematic and well-structured process of testing software applications to uncover defects and errors and check whether it meets the specified requirements. It is an integral process in software development involving different phases, where each phase has its own goals and deliverables. 

By now, STLC and its various phases will be clear to you. Please let me know in the comments if you have any questions. Also, you can check our complete software testing tutorial here-

Software Testing Tutorial

2 thoughts on “STLC | Software Testing Life Cycle”

Leave a Comment