Importance of STLC In Software Testing

STLC in software testing plays a huge role in the software development life cycle. If you are looking for high-performance, high-quality, error-free, and bug-free software, then there is no alternative to STLC. At the end of the day, bug-free software is all that is needed to create a positive user experience.

STLC, or software testing life cycle, is a process that involves a path of activities performed during the testing phase of software. STLC is not just about finding bugs; it's about ensuring the product meets business requirements, user expectations, and industry standards.

Just as the SDLC lifecycle defines how the software is built, STLC defines how the software is tested and helps to find & remove bugs.

Research shows that 20-40% of the software development lifecycle depends on software testing. STLC is a systematic process for maintaining quality and reliability in testing.

In this blog, we will explore the importance of SLTC in software testing and its various phases.

Let's learn.

What Is STLC in Software Testing

STLC =Detect, Report, and resolve bugs

The software testing life cycle is a part of the software development life cycle (SDLC). It's a series of tests that helps define whether the software has bugs or not. With this process, you can easily find the software errors and maintain the standard quality and effectiveness of testing. 

With STLC, we can ensure the quality of software or mobile apps through its different phases. If the test results are satisfactory, then it's considered for implementation or deployment in the market. 

The software testing life cycle is important for any software development program. If a company avoids this stage before launching the software in the market, it may encounter numerous issues.

Consequence of skipping STLC :

• Poor Software Quality
• Increase the overall cost 
• Customer satisfaction 
• Maintenance headache 
• Lack of documentation 
• Not quality validations and verification

It's not the end, a company or organisation also loses its reputation and customer trust.

Importance of Software Testing Life Cycle

We already know that SDLC contains many essential stages. Each stage has its own specific work to do. Each phase also maintains some methods. STLC works as a shield for those stages. We are aware that STLC helps to detect and fix bugs in those stages.

Not only that, every model, such as the V model, spiral model, waterfall, or other existing models, needs to perform this testing phase before making any software live. It helps identify software or app errors and other bug-related issues. 

Without this phase, a software reaches the actual standard, and in the long run, it fails to meet customer expectations. A considerable role plays STLC phases, including:

• Find out the defect early 
• Ensure the software quality 
• Minimise the software security risk 
• Deliver value to stakeholders 
• Continuous integration and development in many models (Agile model, & DevOps)

Method of Software Testing in STLC

When building software or an app, specific criteria must be followed. For instance, you must select the SDLC model as the first step. Then complete the design for each phase. Each phase has specific criteria to be complete.

After completing all the processes, it will proceed to its final stage. STLC also has some methods to follow. A proper method can lead to a proper result and ensure a 100% success ratio.

There are eight (8) different methods to test any software or mobile app. Include:

• Manual testing 
• Automate testing 
• Unit testing 
• Integration testing 
• System testing 
• Performance testing 
• Security
• Acceptance 

Not only is the method needed to complete the STLC process. There are some techniques as well. Many techniques are available in many resources. Include:

• Black box testing
• White box testing 
• Grey box 
• Boundary value testing 
• Equivalence partitioning
• Error guessing & more

Each technique is followed according to the requirements of the project and patterns.

Types Of STLC In Software Testing

The STLC cycle involves applying multiple types of testing, depending on the project's objectives, scope, and requirements. Each type of testing is used in a different phase. It's essential because it makes sure both functional and non-functional aspects are validated.

It's a checking system before the product is released. Basically, there are two types of STLC in software testing. 

• Functional testing
• Non-functional testing 

Understanding each of these two ensures complete quality assurance before deployment.

Functional Testing

This functional testing involves following the system. That means it checks whether the application meets all specified requirements and performs expected tasks . 

Find the exact output given in the input; that's the work done by the functional testing. Another task is to ensure the software functions correctly for each feature. 

Features such as user authentication, input validations, data processing, calculations, and business workflows. In this testing stage, unit testing, integration testing, system testing, regression testing, and user acceptance testing are the common testing types.

Non-Functional Testing 

If we talk about the non-functional testing stage, then it does not directly follow the specific functions . It deals with the software’s quality attributes. The non-functional testing stage evaluates characteristics such as performance, scalability, usability, security, reliability, and compatibility, assessing how each stage performs and identifying its limitations.

But what are the benefits of it? Exactly!!! The answer is quite simple. It helps to keep software stable and efficient under any conditions. Security testing, performance testing, and usability are the primary types of non-functional testing stages.

Functional testing validates correctness against business needs, while non-functional testing ensures the product delivers a good software experience.

Different STLC Phases In Software Testing

STLC is an organised process without any reason. It increases the software quality and helps to increase the maximum outcome. In summary, STLC ensures testing is thorough, efficient, and aligned. So each phase has some entry criteria and exit criteria.

If a phase does not fulfil the entry criteria, then it's impossible to exit that particular phase. So maintaining every step for each stage is essential. Let's review the processes in STLC for software testing and understand how they apply to custom software development.

Phase 1: Requirement

Test Planning → The foundation phase

The very first phase of the STLC is the requirements phase. This phase is very crucial for STLC in software testing. So, the Quality Assurance team gathers all the relevant data about what needs to be updated. To achieve this, they need to reschedule their meeting with the Business Analyst, Project Manager, or client.

Users or clients need to find out what needs to be tested and what needs to be fixed. To achieve this, you must overcome the numerous obstacles and challenges associated with developing software or apps. Also, learn the objectives and goals of this project.

Key notes in the requirements phase:

• Reviewing functional and non-functional requirements data.
• Identifying testable requirements.
• Find out ambiguities, inconsistencies, or gaps in documentation.
• Understanding user expectations and regulatory constraints.

After doing all that,

The QA team gathers all the requirements and starts to work according to the directions.

Why do we need this phase?

• To set the foundations
• Ensure the clarity and alignment
• Collect testable requirements 
• Costly errors
• Helps to guide planning & more

Entry Criteria:

• Approved Software Requirement Specification (SRS) document
• Precise functional and non-functional requirements
• Access to stakeholders, clients, and customers for clarifications

Exit Criteria:

• Testable requirements identified
• Requirement Traceability Matrix (RTM) created 
• All documented and clarified

Phase 2: Plan for Test

Test Planning → The Strategy Phase

After gathering all the requirements and discussing them with stakeholders and developers, once everything is clarified, the next phase begins. The very next phase is planning for the test. In this phase, you need to focus on strategy and planning. The QA team focuses first on the timeline. 

How many days, months, or years will it take to complete this project? The cost is also important. Please find out the total cost and research it for better results. Then, the steps involve assigning the member to different sections, so that each part has specific tasks for individual work. 

Everything in this world is now automated or tool-based. AI can also sometimes give a better output . Select the tools that can provide direction or automate your work. After that, select the text technique as well. Either white box or the black box, and check the text levels like (integrations, unit & more ).

Key Activities at a glance:

• Scope definition 
• Strategy creation 
• Resource allocation
• Effort estimation 
• Risk analysis 
• Tool selection 

Finally, follow a proper plan so that every work goes according to the plan.

Why do we need to follow this test phase?

A proper plan helps prevent disorganization and unnecessary costs. Proper planning also ensures stakeholders have realistic expectations about timelines and coverage. Without an appropriate plan, costs may rise, deadlines slip, and critical areas may remain untested.

Entry Criteria:

• Approved requirements document (SRS/BRD)
• Project schedule and scope defined
• Resource availability check & confirmed

Exit Criteria:

• Completed and reviewed the Test Plan document
• Identified testing tools, resources, and environment needs
• Risk analysis and mitigation plan ready

Phase 3: Test Case Development

Test Case Development → The Blueprint Phase

Once phase 2 is complete, the third phase is unlocked. The third phase is test case development. You can call it a blueprint phase. It's about designing and refining test cases for phase 2. QA team ready to create the actual scripts and data sets in this phase.

According to Phase 1 and Phase 2, it's time to conduct some tests on the development software or apps. This phase provides access to all team members, enabling them to identify any errors or limitations in task assignment.

Key Activities in Phase 3:

• Detailed test cases (input data, execution steps, and expected results)
• Preparing test data (dummy user accounts, payment details, sample orders)
• Developing automation scripts (if needed)
• Recheck test cases for performance & getting approval

Why do we need to follow this test phase?

The test case development phase ensures the overall project software quality and consistency. Without a well-written test case, it can lead to later unwanted costs and low-quality products.

Entry Criteria:

• Approved test plan and requirement documents
• Access to the requirement traceability matrix

Exit Criteria:

• Test cases created, reviewed, and baselined
• Test data prepared and validated
• Scripts developed and reviewed

Phase 4: Test Environment Setup

Test Environment Setup → The Preparation Phase

A successful project quite depends on a proper environment setup. A software engineer needs an appropriate setup and environment to do their best work. Just like software, tools, and accessories, their setup requires checking all related tests.

In this phase, the QA team needs to set up the required software and device. A device like Android or IOS. Not only check it on a mobile device, but also check it on different operating systems for any defects or errors. Prepare all the automation tools, like Appium, Katalon, and Others. 

After completing environmental development, physical software setup, and evaluation environment setup, it's time to perform smoke tests for the software or app development.

Key Activities in Phase 4:

• Setting up required hardware (servers, devices)
• Installing necessary software (databases, operating systems, browsers)
• Configuring test environments (staging, QA, or pre-production)
• Validating readiness by performing a smoke test

Why do you need this phase for STLC in software testing ?

Without a proper environment, software testing results might not be as good as expected. You may experience instability, and testers may report false defects or miss real ones, which can affect release quality.

Entry Criteria:

• Availability of hardware, software, and tools
• Approved environment setup plan
• Access to necessary test data

Exit Criteria:

• Test environment ready and validated
• Smoke test executed successfully
• Test environment sign-off received

Phase 5: Test Executions

Test Execution → The Action Phase

When all the objectives and environment are well enough, it's action time. The QA team develops all the necessary actions, including test cases, test scripts, and test data. The test is done manually or automatically, depending on the requirements.

After all the tests, find out the errors and try to resolve them. Discuss with the developer to resolve issues, understand the outcome, and explore ways to improve it to achieve expected results.

Key activities of test executions in STLC in software testing 

• Executing manual or automated test cases.
• Actual results are compared against expected results.
• Logging defects into a bug tracking tool 
• Performing retesting (to verify fixes)
• Regression testing (to ensure fixes didn't break other features)

Why do you need this phase? 

Without this phase, you don't measure the quality of the project. With that, you can find out the errors and bugs. Otherwise, it creates a major production issue later.

Entry Criteria:

• Completed test cases with test data
• Test environment set up and validated
• Entry sign-off from QA lead/test manager

Exit Criteria:

• All planned test cases executed
• All defects logged and tracked
• Regression and re-testing completed
• Test execution report prepared

Phase 6: Test Circle Closure

Test Cycle Closure → The Evaluation Phase

It's finally the last phase of STLC in software testing. It means the QA team completes all the testing and resolves all the issues. We can also call it the documentation phase of all the phases above.

It can indicate that the software or app is ready to realise and maintain a good standard. You can also get a detailed report about the total cost, the number of bugs found during the testing session, the time taken, and more.

At a glance, closure stage:

• Test summary report highlighting the overall 
• Holding closure meetings with developers, testers, and stakeholders
• Documenting lessons learned and areas of improvement
• Record the data for future reference

Why is this stage:

This stage indicates the final result and where we need to improve in future. It's also documented all the data for further product updates.

Entry Criteria:

• Test execution completed
• All critical defects fixed and re-tested
• Test summary results available

Exit Criteria:

• Test summary report prepared and shared
• Metrics captured (defect density, pass/fail ratio, test coverage)
• Lessons are well-documented for future improvement

So what do you think? Each phase has a particular task to do. You can proceed to the next phase without completing each one. Let's check an example that can clear each stage of work more clearly. Suppose the project is to develop an online food delivery app.

Example of an online food delivery app 

Working process in STLC in software testing

Five Benefits of Following STLC

Software development is a huge task. STLC and the importance of SDLC are both essential to develop high-quality products. Using an STLC stage in your software development project brings numerous benefits. Some of those are :

Early Detection Of Any Bugs 

The STLC process helps to find out any errors at an early stage. That's a good thing, right before any customer finds out. After the deployment of software, if customers discover multiple errors, it will not be suitable for any organisation. Its effect on the company's reputation and brand value. With this, you can easily find bugs and resolve them. Investing in this stage is obviously a win-win situation. 

Improve The Test Coverage

Each phase of STLC is all about proper planning and a well-maintained process. So, it helps to improve the test coverage process of the development project. Proper test planning, case design, and execution guarantee that all functional and non-functional requirements are validated.

Provide Rich User Experience 

A rich user experience is always essential for any kind of product in any sector or any industry. No one recommends slow, buggy, and difficult-to-navigate types of software. The software testing life cycle encompasses all phases, ensuring that types of errors are fixed and that well-standardized software is deployed. That maintains a rich user experience and proper software. 

Transparency and Documentation

Stlc all the phases are well organised and properly documented. If you need to develop this software in the near future, it helps to find all the necessary files in a well-organised manner. This not only creates transparency between teams & serves as a valuable resource for future projects.

Customer Satisfactions 

According to a PwC study, 73% of customers believe that a positive experience is essential for brand loyalty.

Stlc helps to provide that user experience. By investing in STLC software testing, companies can ensure that their products maintain customer expectations.

As a result, it brings positive reviews,strong reputation and increased user retention in the market. Customers also recommend this software to others, which increases the software's popularity and revenue.

Final Line

Following STLC in software testing ensures a disciplined and predictable testing process. Through this testing process, developers easily detect any bugs, loading issues, or other limitations. Stlc is the solution to improve user expectations and maintain industry standards. It minimises risks, extends quality, saves time, and provides confidence that the final software product is ready for release.

FAQs

What Are The 6 Phases Of STLC?

STLC is the process that helps identify all errors in the project and maintain standard quality. Since the six phases of STLC are 

• Requirement 
• Plan for Test 
• Test Case Development
• Test Environment Setup
• Test Executions 
• Test Circle Closure 

Difference Between STLC and SDLC?

The core difference between STLC and SDLC lies in their meanings: STLC refers to the software testing life cycle, whereas SDLC refers to the software development life cycle. In the SDLC, you need to check the software development process-related work, and on the other hand, STLC software testing-related work.

Which Tools Are Used In STLC?

There are lots of tools available online and offline. But these JIRA, Selenium, TestRail, Bugzilla, HP ALM, and TestNG are the popular ones. 

What Is An Example Of STLC in Real Life?

Yes, for a food delivery app, testers analyse requirements, plan tests, write cases, execute them, report bugs, and close with a summary report.

What Is The Cost Of Maintaining This Stage In SDLC?

It really depends on the requirements of the project. You can discuss your requirements with the best software development company. They provide you with the estimated cost, and then you select the best option. 

How Does Software Testing Compromise Development Costs?

With the help of STLC, you can easily identify and fix defects early in the development process. Early detection and resolution of issues help prevent costly post-release fixes. 

Which SDLC Model Uses STLC?

There are some differences between each model, but many of them use STLC in their development stage. Include :

• Waterfall model 
• Agile model 
• V-Model model
• Spiral model
• Iterative