Guide to SDLC , STLC & V-Model

This tutorial explains in detail the Software/System Development Life Cycle (SDLC) like the Waterfall cycle & Iterative cycle like RAID & Agile. It then proceeds to explain the V-Model of testing and STLC(Software Test Life Cycle).

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Video Transcript with Key Takeaways Highlighted:

  • Suppose, you are assigned a task, to develop a custom software for a client.
  • Each block below represents a step required to develop the software.
  • Irrespective of your technical background, try and make an educated guess about the sequence of steps you will follow, to achieve the task
  • The correct sequence would be.
  • Gather as much information as possible about the details & specifications of the desired software from the client. This is nothing but the Requirements gathering stage.
  • Plan the programming language like java , php , .net ; database like oracle , mysql etc which would be suited for the project. also some high level functions & architecture. This is the Design Stage.
  • Actually code the software. This is the Built Stage.
  • Next you ,Test the software to verify that it is built as per the specifications given by the client. This is the TEST stage.
  • Once your software product is ready , you may to do some code changes to accommodate enhancements requested by the client. This would be Maintenance stage.
  • All these levels constitute the waterfall method of software development lifecycle.As you may observe, that testing in the model starts only after implementation is done.
  • But if you are working in large project, where the systems are complex,  its easy to miss out key details in the requirements phase itself. In such cases , an entirely wrong product will be delivered to the client. You will have to start a fresh with the project
  • Or if you manage to note the requirements correctly but make serious mistakes in design and architecture of you software you will have to redesign the entire software to correct the error.
  • Assessments of thousands of projects have shown that defects introduced during requirements & design make up close to half of the total number of defects
  • Also, the costs of fixing a defect increases  across the development life cycle. The earlier in life cycle a defect is detected, the cheaper it is to fix it. As the say, "A stitch in time saves a nine"
  • To address this concern , the V model of testing was developed where for every phase , in the Development life cycle there is a corresponding Testing phase
  • The left side of the model is Software Development Life Cycle - SDLC
  • The right side of the model is Software Test Life Cycle - STLC
  • The entire figure looks like a V , hence the name V - model
  • You a find a few stages different from the waterfall model.
  • These differences , along with the details of each testing phase will be discussed in later tutorial
  • Apart from V model , there are iterative development models , where development is carried in phases , with each phase adding a functionality to the software.
  • Each phase comprises of, its own independent set of development and testing activities.
  • Good examples of Development lifecycles following iterative method are Rapid Application Development, Agile Development
  • Before we close this software testing training a few pointers -
  • You must note that, there are numerous development life cycle models. Development model selected for a project, depends on the aims and goals of that project
  • Testing is not a stand-alone activity and it has to adopt with the development model chosen for the project.
  • In any model, testing should performed at all levels i.e. right from requirements until maintenance.


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