In the realm of software quality assurance (QA), two core concepts underpin the successful delivery of defect-free software: the Software Development Life Cycle (SDLC) and the Software Testing Life Cycle (STLC). These structured frameworks guide how teams build, test, and release applications efficiently and consistently. While SDLC governs the overall process of software creation, STLC […]
In the realm of software quality assurance (QA), two core concepts underpin the successful delivery of defect-free software: the Software Development Life Cycle (SDLC) and the Software Testing Life Cycle (STLC). These structured frameworks guide how teams build, test, and release applications efficiently and consistently.
While SDLC governs the overall process of software creation, STLC ensures the quality and performance of the product through systematic testing. This article breaks down both models, compares their roles, and shows how they align with modern Agile and DevOps practices to deliver robust, high-quality software.
SDLC (Software Development Life Cycle) is a systematic process used by software development teams to plan, design, build, test, and deploy software products. It ensures that all aspects of software creation follow a disciplined approach, minimizing risks and maximizing value.
PhaseDescriptionRequirement AnalysisGathering business needs and user expectationsPlanningDefining scope, timeline, budget, and resourcesDesignArchitecting system structure, UI, and workflowsDevelopmentCoding and building the applicationTestingValidating the system for bugs, security, and performanceDeploymentReleasing the software to users or productionMaintenanceSupporting and updating the live system
Popular SDLC Models: Waterfall, Agile, V-Model, Spiral, Incremental
STLC (Software Testing Life Cycle) is a set of defined activities conducted by QA teams to ensure software meets defined quality standards. It begins as early as the requirements phase and continues until test closure, aligning tightly with the SDLC process.
PhaseDescriptionRequirement AnalysisReviewing requirements from a test perspectiveTest PlanningDefining scope, resources, strategy, and timelinesTest Case DevelopmentCreating test cases and preparing test dataTest Environment SetupInstalling tools, configuring environmentsTest ExecutionRunning tests and reporting bugsTest ClosureAnalyzing results, documenting reports, lessons learned
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Note: In Agile, STLC activities start as soon as requirements are gathered — even before development begins.
AspectSDLC (Software Development)STLC (Software Testing)FocusEnd-to-end software creationQuality assurance and defect detectionParticipantsDevelopers, architects, project managersTesters, QA engineers, test leadsStarting PointBegins with requirement gatheringBegins with test requirement analysisInvolves Testing?Yes, as one phaseEntire life cycle dedicated to testingOutputWorking software productTested, validated software with defect reports
Both cycles complement each other and are tightly integrated in Agile and CI/CD workflows.
In modern practices like Agile, DevOps, and CI/CD, SDLC and STLC operate in tandem, enabling faster feedback loops and higher-quality output.
This synchronized process enhances software quality, reduces time to market, and minimizes post-release defects.
Mastering both SDLC and STLC empowers QA professionals to:
Q1: Is STLC a part of SDLC?A: Yes. STLC is one of the integral components of the overall SDLC, focusing entirely on quality assurance.
Q2: Can testing start before development is complete?A: Absolutely. In Agile and DevOps, testing begins with requirement analysis and progresses alongside development.
Q3: Which comes first — SDLC or STLC?A: SDLC initiates the project, but STLC starts as soon as requirements are available, running in parallel throughout.
Q4: Why is aligning STLC with SDLC important in QA?A: It ensures better coordination, fewer defects, and faster release cycles — a key advantage in competitive software markets.
Q5: Are SDLC and STLC relevant in automation testing?A: Yes. Automation strategies are planned during STLC and integrated within the SDLC pipeline for faster, repeatable tests.
A deep understanding of SDLC and STLC is crucial for building high-quality software that meets both business goals and user expectations. These life cycles don’t operate in isolation — they are collaborative, interdependent, and essential in today’s fast-paced development landscape.
At Testriq QA Lab LLP, we integrate both SDLC and STLC best practices to ensure that every product we test meets industry standards, functional excellence, and user satisfaction.
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