SDLC & STLC

Software Development Life Cycle, or Software Development Process, defines the steps/ stages/ phases in the building of software.
There are various kinds of software development models like:

• Waterfall model
• Spiral model
• Iterative and incremental development (like ‘Unified Process’ and ‘Rational Unified Process’)
• Agile development (like ‘Extreme Programming’ and ‘Scrum’)

Models are evolving with time and the development life cycle can vary significantly from one model to the other. It is beyond the scope of this particular article to discuss each model. However, each model comprises of all or some of the following phases/ activities/ tasks.
SDLC IN SUMMARY

• Project Planning
• Requirements Development
• Estimation
• Scheduling
• Design
• Coding
• Test Build/Deployment
• Unit Testing
• Integration Testing
• User Documentation
• System Testing
• Acceptance Testing
• Production Build/Deployment
• Release
• Maintenance

SDLC IN DETAIL

• Project Planning
  • Prepare
  • Review
  • Rework
  • Baseline
• Requirements Development [Business Requirements and Software/Product Requirements]
  • Develop
  • Review
  • Rework
  • Baseline
• Estimation [Size / Effort / Cost]
  • <same as the activities/tasks mentioned for Project Planning>

• Scheduling
  • <same as the activities/tasks mentioned for Project Planning>
• Designing [ High Level Design and Detail Design]
  • <same as the activities/tasks mentioned for Requirements Development>
• Coding
  • Code
  • Review
  • Rework
  • Commit
  • Recode [if necessary] >> Review >> Rework >> Commit
• Test Builds Preparation/Deployment
  • Build/Deployment Plan
    • Prepare
    • Review
    • Rework
    • Baseline
    • Revise [if necessary] >> Review >> Rework >> Baseline
  • Build/Deploy
• Unit Testing
  • Test Plan
    • Prepare
    • Review
    • Rework
    • Baseline
    • Revise [if necessary] >> Review >> Rework >> Baseline
  • Test Cases/Scripts
    • Prepare
    • Review
    • Rework
    • Baseline
    • Execute
    • Revise [if necessary] >> Review >> Rework >> Baseline >> Execute
• Integration Testing
  • <same as the activities/tasks mentioned for unit testing>
• User Documentation
  • Prepare
  • Review
  • Rework
  • Baseline
  • Revise [if necessary] >> Review >> Rework >> Baseline
• System Testing
  • <same as the activities/tasks mentioned for Unit Testing>
• Acceptance Testing[ Internal Acceptance Test and External Acceptance Test]
  • <same as the activities/tasks mentioned for Unit Testing>
• Production Build/Deployment
  • <same as the activities/tasks mentioned for Test Build/Deployment>
• Release
  • Prepare
  • Review
  • Rework
  • Release
• Maintenance
  • Recode [Enhance software / Fix bugs]
  • Retest
  • Redeploy
  • Rerelease

Notes:

• The life cycle mentioned here is NOT set in stone and each phase does not necessarily have to be implemented in the order mentioned.
• Though SDLC uses the term ‘Development’, it does not focus just on the coding tasks done by developers but incorporates the tasks of all stakeholders, including testers.

There may still be many other activities/ tasks which have not been specifically mentioned above, like Configuration Management. No matter what, it is essential that you clearly understand the software development life cycle your project is following. One issue that is widespread in many projects is that software testers are involved much later in the life cycle, due to which they lack visibility and authority (which ultimately compromises software quality).


Software Testing Life Cycle (STLC) defines the steps/ stages/ phases in testing of software. However, there is no fixed standard STLC in the world and it basically varies as per the following:

• Software Development Life Cycle
• Whims of the Management

Nevertheless, Software Testing Life Cycle, in general, comprises of the following phases:

Phase	Activity	Deliverables	Necessity
Requirements/ Design Review	You review the software requirements/ design (Well, if they exist.)	‘Review Defect’ Reports	Curiosity
Test Planning	Once you have gathered a general idea of what needs to be tested, you ‘plan’ for the tests.	Test Plan Test Estimation Test Schedule	Farsightedness
Test Designing	You design/ detail your tests on the basis of detailed requirements/design of the software (sometimes, on the basis of your imagination).	Test Cases / Test Scripts /Test Data Requirements Traceability Matrix	Creativity
Test Environment Setup	You setup the test environment (server/ client/ network, etc) with the goal of replicating the end-users’ environment.	Test Environment	Rich company
Test Execution	You execute your Test Cases/ Scripts in the Test Environment to see whether they pass.	Test Results (Incremental) Defect Reports	Patience
Test Reporting	You prepare various reports for various stakeholders.	Test Results (Final) Test/ Defect Metrics Test Closure Report Who Worked Late & on Weekends (WWLW) Report [Depending on how fussy your Management is]	Diplomacy

Note that the STLC phases mentioned above do not necessarily have to be in the order listed; some phases can sometimes run in parallel (For instance, Test Designing and Test Execution). And, in extreme cases, the phases might also be reversed (For instance, when there is Cursing prior to Testing).
Interestingly, no matter how well-defined a Software Testing Life Cycle you have in your project or organization, there are chances that you will invariably witness the following widely-popular cycle:

• Testing
• Cursing

In this type of STLC, you skip phases like design review, test planning, etc – in the hope that the skipping will save you some time and/or cost [But, it never does].