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A Complete Guide to Software Testing Life Cycle (STLC)

Shakura Banu
Published: December 22, 2022

Software testing is the process of evaluating a software product to detect errors and failures and ensure its suitability for use. It can be performed manually (where testers use their skill, experience, intuition, and knowledge) or automatically (where the tester’s actions are guided by a test script).

The fundamental objective of the test process is to ensure that all specified requirements of a software system have been met by the development process and that no undetected errors remain in the system. However, the overall aim of testing is to provide customer or end-user value by detecting defects as early as possible.

Testing occurs in different phases throughout the Software Development Life Cycle (SDLC). Testing may also occur after the completion of each phase or after certain checkpoints within each development phase. The different phases through which a piece of software passes before it is released for use are called the Software Testing Life Cycle (STLC).

In this article on STLC, we will discuss the fundamentals of software testing, the phases of the software testing life cycle, methodologies, and their best practices.

Let’s dive in!

What Is the Software Testing Life Cycle?

The STLC is an iterative, cyclical process that has the goal of preventing errors in the software. It includes test analysis, planning, designing, setup, execution, and test closure activities. Due to the complexity of the software, it is impossible to guarantee that a product will be free of errors if only one test is performed. Therefore, multiple tests are performed on every phase of the Software Testing Life Cycle.

STLC Chart

There are different types of tests that can be implemented alongside each other or separately at any time during the life cycle. Examples include usability testing, regression testing, exploratory testing, and sanity testing – for all of these different types, there are many subcategories. Each category has its own special purpose and will vary depending on the circumstances.

The STLC has the following phases, which we will discuss in detail in the later sections:

  • Requirement Analysis
  • Test Planning
  • Test Case Designing and Development
  • Test Environment Setup
  • Test Execution
  • Test Cycle Closure

Characteristics of the Software Testing Life Cycle

  • STLC is a step-by-step method for ensuring high-quality software.
  • Improves the consistency and efficiency of the agile testing process.
  • As soon as needs are determined or the Software Requirements Specification (SRS) document is ready, the STLC process should begin.
  • Defines goals and expectations clearly for each project aspect.
  • The tester can analyze and establish the scope of testing and write effective test cases while the software or product is still in the early stages of the STLC. It aids in the reduction of the test cycle time and the provision of higher product quality.
  • Ensures the features are tested and passed before adding the additional features.

The Difference Between SDLC and STLC

Software Development Life Cycle, or SDLC, is one of the most important phases in the development of any software. During this phase, various steps are taken to develop a product and make it market-ready. Software testing is one of the most critical parts of the SDLC process. It has an entire life cycle known as Software Testing Life Cycle or STLC. So, what’s the difference between SDLC and STLC?

Focuses on developing a product.Focuses on product testing.
It helps in developing good quality software.It helps in making the software defects-free.
Understanding user needs and creating a product that is beneficial to them.Understanding the products development requirements and ensuring it performs as intended.
In SDLC, the business analyst gathers the requirements and creates a Development Plan.In STLC, the QA team analyzes requirements like functional and non-functional documents and creates a System Test Plan.
In SDLC, the development team creates high and low-level design plans.In STLC, the test analyst creates the Integration test plan.
SDLC is responsible for collecting requirements and creating features.STLC is responsible for creating tests adapted to the collected requirements and verifying that features meet those requirements.
Before testing, the SDLC phases are completed.After the SDLC phases are completed, the STLC phases begin.
The end goal is to deliver a high-quality product that users can utilize.The ultimate goal is to uncover bugs in the product and submit them to the development team so they can be fixed.

Software Testing Life Cycle Phases

It’s important to understand the phases of the Software Testing Life Cycle to make better decisions about how to test your software. One critical aspect of the testing lifecycle is determining which phase of testing to perform on your software. The first step in this process is to determine whether you need to perform testing on your product or not.

If your product is an app that collects data, it will have less need for testing than if it were a banking website that processes financial transactions. Some products may undergo all phases of testing, while others may be tested only partially. For example, a website that exists purely as a marketing tool might not need to go through any tests other than usability tests.

Testing can happen at any time, and each phase should be performed at least once before moving on to the next. Every phase is independent of the rest, so you can perform only one if necessary.

A typical Software Testing Life Cycle consists of the following phases; let’s have a detailed understanding of each phase.

Requirement Analysis

Requirement analysis is the initial phase in the Software Testing Life Cycle. This phase examines functional and non-functional requirements from the testing perspective to identify the testable needs. Customers, solution architects, technical leads, business analysts, and other stakeholders communicate with the quality assurance team and comprehend the clients’ requirements to tailor the tests to the customer’s specifications.

Entry Criteria

  • Specification document and application architecture are two documents that must be available.
  • The acceptance criteria and the availability of the above documents must be clearly established.

Activities in the Requirement Analysis Phase

  • Identifying and prioritizing the requirements.
  • Brainstorming sessions for the feasibility and requirement analysis.
  • Creating a list of the questions that the client, solution architect, technical lead, business analyst, etc., need to answer.

Test Planning

With the information gathered in the requirement analysis in the previous phase, the QA team moves a step ahead in the direction of planning the testing process. The most crucial phase of the Software Testing Life Cycle is test planning or test strategy. All of the testing strategies that will be utilized to test the program are defined during this phase.

The test lead determines the cost estimates and efforts for the entire project at this phase. Here, a variety of test activities are planned and strategized together with the analysis of resources, which increases the effectiveness of the planning phase and aids in achieving the testing target.

Software testing can’t be valued without effective tools, especially when you are performing automation testing. Choosing the right tool for software testing is planned in this phase. There are various tools out in the market for performing software testing. Choosing cloud-based automation testing tools like LambdaTest is the right choice when you want to test at scale.

Entry Criteria

  • Documents containing requirements.
  • There should be a report on automation criteria provided.

Activities in the Test Planning Phase

  • The objectives and scope are described.
  • Selecting the testing types to be carried out and the unique approach for each.
  • Roles and Responsibilities are determined and assigned.
  • Locating the testing resources and equipment needed for the test.
  • Choosing the right testing tools.
  • Calculating the time and effort needed to complete the testing activities.
  • Risk analysis is being done.

Test Case Designing and Development

The requirements have been examined, and the QA team has created a test plan in response. It’s time to be creative and shape this test strategy by turning it into test cases. To check and validate each test plan, test cases are devised and developed based on a test strategy and specific specifications.

Designing test cases in the STLC is a very important process as it will help determine the defects in the product. It can also be called defect identification or defect analysis. In order to design the test cases, first, we need to have a requirement document that will define the scope of functional and non-functional testing.

This requirement document can be prepared by business analysts, and it should also include all possible user scenarios of the software product. Once we have the requirement document, we will go for test case designing.

Designing test cases involves two steps:

1. Identification of test cases

2. Analysis of test cases 

The first step is to identify all the possible test cases which can cover all the user scenarios, and then finally, after analyzing them, we need to remove the test cases which are not fit for execution or the test cases which have low priority or the test cases which may not be able to find out any defect. The QA team begins writing effective test cases when the test design step is completed.

Entry Criteria

  • The specifications documents.
  • The feasibility report on automation.

Activities in the Test Case Designing and Development Phase

  • Test cases are designed, created, reviewed, and approved.
  • Existing test cases that are pertinent are examined, revised, and approved.
  • If necessary, automation scripts are created, examined, and approved.

Test Environment Setup

Post designing and developing the test cases, to establish and replicate the ideal conditions and environmental factors to conduct actual testing activities, the software testing process needs an adequate platform and environment that includes the essential and necessary hardware and software.

This phase consists of preparing the testing environment. The test environment establishes the parameters under which the software will be evaluated. Because this is a stand-alone activity, it can run concurrently with the test case development process.

The test environment differs from one organization to another. In some circumstances, the testing environment is built up by the developer or tester, while in others, the testing environment is set up by the clients based on their needs and requirements.

The testing team prepares for smoke testing while the customer or developer prepares the test environment. The purpose of smoke testing is to validate the test environment by determining its readiness and stability.

Entry Criteria

  • The test strategy should be readily available.
  • Smoke test cases should be readily available.
  • The results of the tests should be available.

Activities in the Test Environment Setup Phase

  • The test data is set up.
  • The necessary hardware and software have been gathered and a test environment checklist has been created.
  • Network configurations and a test server have been set up.
  • The process for managing and maintaining test environments is outlined and explained.
  • The atmosphere is smoke tested to ensure readiness.

Test Execution

The QA team is now prepared to engage in some practical testing operations as they have the test cases, test data, and the appropriate testing environment. The testing team executes the test cases in this phase based on the test cases and test planning prepared in the preceding phases, namely the test planning and test case development phases.

The test cases that are passed are given a score. When a test case fails, a bug tracking system is used to communicate the defect or problem to the development team.

These bugs can also be connected to a test case for future reference. In an ideal world, every failed test case would be associated with a defect. After the development team has addressed the bug, the identical test case is rerun to ensure that it is indeed fixed and works as expected.

A report is generated that displays the amount of passed, blocked, failed, or not run test cases, among other information.

Entry Criteria

  • Testing strategy documents.
  • Examples of test scenarios.
  • Data from the tests.

Activities in the Test Execution Phase

  • Following the test plan, test cases are executed.
  • Contrasting the outcomes achieved with those anticipated.
  • Locating and spotting flaws.
  • Recording the flaws and reporting the found bugs.
  • Mapping faults to test cases and updating the traceability matrix for requirements.
  • Retesting after the development team has corrected or eliminated a bug.
  • Testing for regression (if required).
  • Tracking a flaw until it is fixed.

Test Cycle Closure

The completion of the test execution phase and delivery of the software product marks the beginning of the test closure phase. This is the phase in which the entire cycle is evaluated. Other testing-related characteristics, such as quality attained, test coverage, test metrics, project cost, adherence to deadlines, etc., are taken into account and analyzed in addition to the test results.

The team also analyzes the aspects of the Software Testing Life Cycle process that went well and those that may be improved. To determine the severity and issues, the test case report is generated. The test metrics and closure reports are created after the test cycle is completed.

Entry Criteria

  • Report on the execution of the test case.
  • Report on a flaw.
  • The execution of the test cases should be completed.

Activities in the Test Cycle Closure Phase

  • Review the entire testing procedure.
  • Discussions take place regarding the need to modify the exit criteria, test plan, test cases, etc.
  • Analysis and examination of test results.
  • All test deliverables, including the test plan, test strategy, test cases, and others, are gathered and kept up to date.
  • Test metrics and the test closure report have been created.
  • The severity and priority of the defects are ordered.

Methodologies of Software Testing Life Cycle

In software testing, there are various methodologies to carry out the software testing processes.

There are four types of methodologies:

  1. Waterfall Model
  2. V Model
  3. Spiral Model
  4. Agile Model

Waterfall Model

One of the earliest process models to be introduced was the waterfall Model. It is quite basic and straightforward to use. It functions similarly to a downward-flowing waterfall. Each phase should be finished before the execution of the next phase in this model, ensuring that no phases overlap.

There are five phases in the waterfall model, which are completed one after the other. They are:

  • Requirement analysis
  • System design
  • Implementation
  • System testing
  • System deployment
  • System maintenance

Waterfall Model

Before testing begins, all needs are determined in the first step, referred to as the requirement analysis phase. The developers build the projects workflow in the next step, known as the system design phase. The intended work from the system design phase is implemented in the implementation phase. The testing step follows, with each modules functionality being validated against the criteria.

The next phase is the deployment phase, followed by the maintenance phase, which is an ongoing process. During this phase, the developers address any issues arising from the softwares use over time. When a problem occurs, the developer patches it and the software returns to testing. This process is repeated until all flaws have been resolved.

Advantages of the Waterfall Model

  • There is a review procedure and defined deliverables for each phase.
  • There is no overlapping between the phases because they are completed one at a time.
  • It works effectively for projects with well-defined requirements that do not change over the development process.

Disadvantages of the Waterfall Model

  • It does not demonstrate good results for lengthy projects.
  • It carries a great deal of danger and uncertainty.
  • It performs terribly for projects with a high or moderate likelihood of required modifications.
  • For complex, object-oriented tasks, it performs mediocrely.
  • The entire project may be abandoned if the scope is modified along the life cycle.
  • In the last stages of the life cycle, the functional software is produced.


The waterfall model is an out-of-date model with numerous flaws and limitations. As a result, the V-Model was created to overcome those limits.

The verification and validation model is another name for the V-Model. It is seen as a development of the waterfall model. The tasks in the V-Model are completed simultaneously. On the left-hand side, it depicts software development operations, while on the right-hand side, it depicts the testing phases in progress.


It means that each element of the software development cycle is inextricably linked to the phases of software testing. This model likewise follows the waterfall approach, as there are no stages that overlap, and the next phase begins once the previous phase has been completed.

The testing phase must be planned concurrently with the software development phase in this architecture. The verification phase begins after the designing or planning phase, followed by the coding phase, and finally, the validation step.

This phase also includes module design, which ensures that all modules are compatible with one another. The coding step begins after the verification phase is completed.

The coding is carried out in accordance with the standards and rules. The validation phase follows the coding phase. The software is tested, including unit testing, integration testing, system testing, and acceptance testing, to ensure that it meets the customers needs and expectations and that it is defect-free.

Advantages of the V-Model

  • It is simple to comprehend and operate. Its ease of use makes it much more manageable.
  • There is no overlapping of phases.
  • It’s ideal where the needs are clear, such as minor projects.
  • Each phase has its evaluation procedure and set of deliverables.

Disadvantages of the V-Model

  • Not recommended for complex, object-oriented programs.
  • Unsuitable for lengthy projects.
  • Not suitable for projects when there is a medium to high likelihood that a requirement may change during the project.

Spiral Model

The V-Model and the waterfall Model are recommended only for smaller projects where the requirements are specified clearly. Spiral models are suitable for larger projects.

The Sequential Linear Development Model and the Iterative Development Process Model are combined in this paradigm. This means it’s similar to the waterfall approach but focuses on risk assessment. In the spiral mode, a particular activity is done in one iteration. This is why it is called spiral.

The same procedure is followed for every spiral created to construct the whole software. There are four phases in the spiral model. They are:

  • Identifying objectives
  • Risk analysis
  • Develop and test
  • Review and evaluate

The sole variation between the phases of the waterfall and spiral model is the risk analysis.

Spiral Model

Advantages of the Spiral Model

  • Unlike the previous two models, it enables changes to be accommodated. However, the requirements should be expressed clearly and should not change throughout the process.
  • It enables users to test the system at an early stage.
  • Requirements are captured more precisely.
  • It provides for the division of the development process into smaller segments, allowing for the creation of the riskier parts early, resulting in better and more exact risk management.

Disadvantages of the Spiral Model

  • The procedure is very intricate.
  • It is impossible to predict the projects completion date in advance.
  • Low-risk initiatives shouldn’t employ it because it can be costly and unnecessary.
  • There is no end to the spiral iteration.
  • As a result of the several intermediary steps, excessive documentation is required.

Agile Model

To overcome these challenges, longer iterations of testing and development are used in the agile paradigm throughout the software testing life cycle. It is currently the most popular model. If you are still working on the waterfall methodology, it is high time to move to the agile methodology. Here are some of the points you need to know while moving from waterfall to agile testing.

Customers have the ability to make adjustments to the project to improve it and eliminate defects. In other words, any errors discovered during testing can be rectified or amended on the spot without interrupting the testing process.

Agile Model

Teams must now automate their test cycles due to the current trend in enterprises toward agile development. This enables them to advertise new features more quickly and gain an advantage. There are seven phases included in the agile methodology. They are:

  • Plan
  • Design
  • Develop
  • Test
  • Deploy
  • Review
  • Launch

It is essential to follow the phases one after the other. It’s also critical to remember that to ensure apps are prepared for the real world, they must be tested in real-world user conditions. This also implies that teams must have immediate access to real devices with real operating systems and browsers loaded for testing. Now, keeping up with such an internal device lab requires a lot of money, time, and effort.

The best way to avoid cost and effort is to opt for a cloud-based web testing platform. LambdaTest, a cloud-based cross-browser testing platform, is the right fit here. It provides a cloud-based scalable infrastructure and provides an online browser farm of 3000+ browsers, devices, and OS combinations. You can use LambdaTest with the online Selenium Grid’s power to run thousands of parallel tests in a matter of seconds, reducing test execution time and providing faster feedback on code changes.

Advantages of the Agile Model

  • The processes are divided into many individual models in the agile model so that developers can work on them separately.
  • It presents a method for software testing and development that is iterative and incremental.
  • It gives the consumer an early peek at the project and allows them to make regular decisions and modifications.
  • When compared to the other models, the agile technique is considered an unstructured model.
  • Between testing sessions, problems, errors, and defects can be corrected.
  • It necessitates less planning, and the project, or the testing process, is completed in short iterations.

With plenty of advantages, it is suitable for organizations to stick to the agile methodologies.

Best Practices of Software Testing Life Cycle

Below are some of the best practices that are followed in the Software Testing Life Cycle.

  • When deciding on the scope of testing, consult with important business users.
  • User feedback is used to identify essential business processes.
  • As they consume most of the users time and resources, it ensures that the test strategy covers testing for those essential business operations.
  • Determine the most common faults or problems that negatively influence the user experience.
  • Testing is planned with a clean user experience for important processes.
  • Testing is planned to ensure that the product meets all user requirements.


Identifying faults in the last stage of an SDLC is no longer an effective approach. A company must also concentrate on a variety of other daily duties. Spending too much of your valuable time testing and correcting bugs can stifle productivity. After all, it will take longer to produce less output.

It’s critical to make efficient use of time and resources to make the testing process go more smoothly. Following a systematic STLC allows you to fix bugs quickly and improves your works quality.

Happy testing!