Software Development Lifecycle Models

Software Development Lifecycle Models

Introduction: Software Development Lifecycle Models – Agile Testing (SDLC) models represent the processes and phases that a software project undergoes from its initiation to completion. Different SDLC models exist, such as Waterfall, Agile, Iterative, and Spiral. Each model has its unique characteristics, advantages, and disadvantages.

Software Development and Software Testing

The relationship between software development and software testing is integral to the success of a project. In traditional Waterfall models, testing is often a distinct phase that follows development. In Agile methodologies, testing is typically performed concurrently with development in iterative cycles.


In an Agile environment, a software development team might follow the Scrum framework. Testing activities, such as creating and executing test cases, occur alongside the development sprints. This allows for continuous feedback and adjustments throughout the development process.

Software Development Lifecycle Models in Context

Different projects and organizations may choose SDLC models based on their specific needs and constraints. Understanding the context in which each model is applied is crucial. For example, a large-scale, complex project might benefit from an iterative or Agile approach, while a project with well-defined requirements may opt for a Waterfall model.


A safety-critical software project, such as developing software for a medical device, may prioritize a V-model or Iterative model to ensure thorough testing at each stage, minimizing the risk of defects.

Test Levels

Test levels represent the different stages of testing within the SDLC. Each level focuses on specific aspects of the software, progressively ensuring its quality.

Component Testing

Also known as unit testing, component testing involves testing individual units or components of the software in isolation. The goal is to ensure each unit functions as intended.


For a web application, component testing might involve testing individual functions or methods within the code, such as validating user input or processing data.

Integration Testing

Integration testing verifies the interaction between different components or units. It ensures that integrated components work together as expected.


In the integration testing of a banking system, individual modules handling account creation and fund transfers are tested together to validate that they interact correctly and maintain data consistency.

System Testing

System testing evaluates the entire system’s functionality and performance. It tests the system as a whole, considering its compliance with specified requirements.


In system testing for an e-commerce platform, the entire application is tested to verify features such as product catalogue, shopping cart functionality, and payment processing.

Acceptance Testing

Acceptance testing determines whether the software meets user requirements and is ready for deployment. It includes User Acceptance Testing (UAT) conducted by end-users.


In UAT for a customer relationship management (CRM) system, end-users might validate features such as lead management, contact tracking, and reporting to ensure they meet business needs.

Test Types

Test types categorize testing based on the purpose or characteristics of the tests.

Functional Testing

Functional testing verifies that the software functions according to specified requirements. It ensures that each feature behaves as expected.


For a word processing application, functional testing might involve validating features like spell-check, formatting, and document saving.

Non-functional Testing

Non-functional testing assesses aspects other than functionality, such as performance, usability, security, and scalability.


In non-functional testing for a web application, performance testing might evaluate the system’s response time under various user loads to ensure it meets performance requirements.

White-box Testing

White-box testing, also known as structural or glass-box testing, involves testing with knowledge of the internal code structure. It includes techniques like statement and decision coverage.


White-box testing for a software module might involve examining the code to ensure that all statements are executed and all decision points are tested.

Change-related Testing

Change-related testing focuses on verifying the impact of changes, updates, or modifications to the software. It ensures that new features or fixes do not introduce unexpected issues.


After implementing a software update for a mobile app, change-related testing may involve checking that new features work as intended and do not adversely affect existing functionality.

Test Types and Test Levels

Understanding the relationship between test types and test levels is crucial for effective testing. Different test types may be applicable at various test levels, depending on project requirements.


Unit testing (a test level) may involve functional testing (a test type) to validate individual components’ functionality.

Maintenance Testing

Maintenance testing addresses changes made to the software after its initial development and release.

Triggers for Maintenance

Maintenance testing is triggered by changes such as bug fixes, feature enhancements, or updates to accommodate new technologies.


A software application used for financial calculations may undergo maintenance testing when tax laws change, requiring updates to calculations and reports.

Impact Analysis for Maintenance

Impact analysis assesses the potential effects of changes on the existing system. It helps determine what parts of the system need testing after a modification.


Before implementing a security patch for an e-commerce platform, impact analysis might identify areas that require testing, such as payment processing and user authentication.

participants will gain a comprehensive understanding of how testing is integrated into different phases of the software development lifecycle, the various test levels, the types of tests applied, and the importance of maintenance testing for evolving software systems. This knowledge equips them to make informed decisions about testing strategies and approaches in real-world development scenarios.

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