Software Testing Life Cycle (STLC) Explained

Dec 5, 2023

In the past, enterprises solely focused on the software development cycle (SDLC) and considered testing a part of the process. However, over time, it has become evident that software testing has a life cycle of its own. Testing is no longer limited to finding bugs but now has a broader scope and is necessary right from the beginning of the project as soon as the requirements have been defined.

To ensure you present the perfect product to consumers and provide pleasant user experiences free from bugs, testing must be integrated into SDLC through a sequence of activities that comprise the software testing life cycle (STLC).

software testing is an iterative process for QA teams
Teams help identify and prioritize test requirements.

What Is Software Testing Life Cycle (STLC)?

Contrary to popular belief, software testing is not an isolated activity but a series of systematic activities to help you certify your software product. During software development, phases of the STLC may be performed multiple times until a product is considered suitable for release. In addition to testing the developed product, STLC is also needed for the following reasons:

  • To improve the agile testing process and have product shortcomings removed at the earliest and most profitable stage of development.
  • To help define goals and timelines for each project aspect.
  • To enhance transparency in the software development process.
  • To maximize control over the quality of the product being developed at all stages of the SDLC.
  • To verify that project requirements are met.

It is critical to validate every module of a software or application to ensure the highest possible quality of the end product and its adherence to client and industry requirements. The testing life cycle has six main phases: requirement analysis, test planning, test case development, test environment setup, test execution, and test cycle closure.

Importance of Software Testing Life Cycle

It is always better to prevent a problem than try to fix one after it occurs. This is the goal behind STLC and why testing is required during the development process. No matter how meticulously software is built, it cannot be perfect. There is always a chance that something might have been overlooked, affecting the final product and its performance. STLC ensures every software component is individually examined and verified to be working correctly on its own and in conjunction with others and will continue to do so over time. This helps to identify and address any challenges before the application is ready for consumer use.

Advantages of software testing life cycle include the following:

  • It moves testing activities toward the left side of the project timeline so that they are conducted earlier in the development process. Shift left testing is important in STLC because it helps speed up testing, identify flaws sooner, lower total costs, and reduce time to market.
  • Systematic testing enables teams to uncover and address issues faster, thus speeding up the testing process.
  • Makes it easier to track project progress since tests are performed in phases and with well-defined goals.

Vector illustration of a young man working on his laptop conducting testing activities on software
Early testing helps you detect issues within your product early in the Dev process.

Phases of Software Testing Life Cycle

There are 6 phases in the STLC, each with its own entry and exit criteria. The entry criteria are conditions or goals that must be met to create an appropriate and favorable testing environment. They guarantee the accuracy of the testing process and are finalized and chosen after a comprehensive analysis of the software and business requirements. Exit criteria, however, describe all the requirements that must be met before completing testing in a particular phase. All deliverables to eliminate flaws, bugs, and mistakes must be finished to satisfy the exit criteria.

The activities and deliverables of each phase determine the actions to be performed and the expected results. Additionally, some phases can be performed simultaneously, while others require previous phases to be completed first.

Requirement Analysis

This is the first step of the software testing life cycle and is the only opportunity to fix project flaws at almost no charge. It brings teams together for brainstorming sessions that help identify and prioritize test requirements. Quality assurance works within their teams and cross-functionality to decide how testing will be done and prioritize activities. They also establish if automated testing is feasible, clarify vague requirements, and ensure an appropriate test environment.

In a nutshell, the objectives of the Requirement Analysis phases include the following:

  • To recognize the expected output from the product.
  • To establish blind spots or ambiguities in the specifications.
  • To prioritize testing activities.
  • To establish the feasibility of automated testing.

The actions taken in this stage result in deliverables such as requirements reports and requirement traceability matrixes (RTMs).


Test Planning

In this phase, testing teams develop a strategy for testing the software. All testing strategies are defined in this stage, including the timing, participants, costs, and responsibilities. Some of the activities that take place during the Test Planning phase include:

  • Creating a plan for the testing activities.
  • Estimating the time and effort required.
  • Selecting the most appropriate testing tools.
  • Assigning testing tasks and responsibilities to teams and individuals.

This phase provides the roadmap for the entire testing process. The most crucial delivery generated is the test plan, a document describing the motivation and details of the testing activities for a particular project.

Test Case Development

Test case development only begins after the test planning phase is completed. Based on the test plan, testing teams will design and develop test cases to describe specific steps to be followed, expected outcomes, and data inputs. This is a primarily creative stage in the testing cycle, as teams can choose how they fulfill it.

Test cases will be prioritized based on their effect on the product. They will then be reviewed, updated, approved, and combined in suites. At the end of the phase, testing teams should have a set of comprehensive and accurate test cases that provide accurate coverage of the software application.

Test Environment Set Up

Testing activities need certain conditions or tools to be present to execute developed test cases. These conditions and tools comprise the test environment, including servers, hardware, software, and frameworks that mimic end-user devices.

In summary, Test Environment Setup helps you to:

  • Understand what software and hardware are required
  • Prioritize test environments
  • Set up test environments
  • Smoke test the software built

The expected deliverables from this phase include environment-ready and smoke test results.

Test Execution

This is the magic phase of the software testing life cycle, where developers test a program’s features. Alongside quality teams, they apply test cases within established test environments and compare and document the results against the expected outcomes. Learn how to optimize your Test Execution along with your CI Pipelines.

The main objectives of the Test Execution phase include:

  • Executing tests as specified in the test plan.
  • Document defects and map them to test cases in the requirements traceability matrix (RTM).
  • Retest defective modules.
  • Track defects in closure.

Some deliverables you can expect include defect reports, updated RTM, and results of test cases.

Test Cycle Closure

As the final phase of STLC, Test Cycle Closure involves preparing a test result report. The report summarizes the entire testing process while comparing expected and actual results. The comparisons usually include objectives met, time taken, test coverage, defects found, and total costs.


Software testing life cycle drives efficiency into an otherwise chaotic process by helping you better organize your workflow testing. Software development projects are getting more complex, and enterprises have to keep up with the requirements of the fast-paced market while facing budget limitations and time constraints. Early testing helps you detect issues with your product early in the development process, helping to prevent potentially more significant issues later on. This saves you the cost of returning to fix errors post-launch and the risk of damaging your brand reputation.

However, STLC is still a complex concept and can be a hassle to navigate. By leveraging quality assurance automation platforms, developers, shareholders, testing teams, and other stakeholders can ensure maximum productivity and efficient use of resources.

 Vector illustration of a group of people testing software
Software testing is a series of systematic activities to help you certify your software product.

To build efficient test cycles and increase productivity with quality intelligence, try out TestBrain for free or watch a quick demo to learn how it works.