T09 - VALIDATION AND VERIFICATION

Chapter 8 - Software Verification and Validation

Introduction to Software Testing

• Software testing is a critical process intended to ensure that software meets its requirements and functions as expected before it is used.

• Testing helps identify defects in the software through the execution of programs with artificial data.

• The testing process is part of a larger framework known as verification and validation (V&V).

Types of Testing

Development Testing

• Conducted during the development phase to discover defects as early as possible.

• Includes various tests such as unit testing, component testing, and system testing.

  • Unit Testing: Tests individual components or methods in isolation, ensuring they function correctly.

  • Component Testing: Focuses on testing the interactions between integrated components.

  • System Testing: Tests the integrated system as a whole.

Release Testing

• Performed on a completed version of the software before it is made available to users.

• Aims to validate the functionality and reliability of the software from the end-user perspective.

• Generally considered a black-box testing process.

User Testing

• Involves real users testing the software to provide feedback on its usability, performance, and reliability in their working environment.

• Helps identify issues that may not be apparent in controlled testing environments.

Program Testing Goals

• Primary goals include:

  • Validation Testing: Demonstrates that the software meets specified requirements.

  • Defect Testing: Aims to uncover faults and errors in software behavior.

• Effective testing identifies incorrect outputs and system behavior that doesn’t conform to requirements.

Testing Process Overview

• Validation Testing: Confirms that software functions as intended under expected conditions.

• Defect Testing: Designed to uncover defects through unexpected inputs or interactions.

• Both processes are integral to building confidence in the software's reliability and functionality.

Verification vs. Validation

• Verification: Ensures that the software conforms to its specifications.

• Validation: Confirms that the software meets the actual needs of the user.

Inspections vs. Testing

• Inspections: Focus on reviewing static representations of the software to find defects. They do not involve executing the software and can be applied at any stage of development.

• Testing: Involves dynamic verification; software is executed, and its behavior under test data is observed.

Advantages of Inspections

• Can identify many defects quickly without needing a working version of the software.

• Effective in assessing compliance with quality standards and verifying broader attributes like maintainability.

Review Process

1. Pre-review Activities: Planning and preparing for the review by assembling a team and distributing documents.

2. Review Meeting: Discuss the software/documents with its author and examine it collectively for defects.

3. Post-review Activities: Address any issues identified and ensure all comments are considered in subsequent iterations.

Testing Policies

• Exhaustive testing is impractical; therefore, policies should define minimum requirements for test coverage.

• Examples include testing all functions accessed through menus or verifying inputs under both correct and incorrect scenarios.

Regression Testing

• Conducted to ensure that new changes in the software do not negatively impact existing functionality.

• Automated testing makes this process efficient.

Performance and Stress Testing

• These tests assess the system's reliability and performance under normal and extreme conditions.

• Important for understanding how the system behaves under various loads.

User Testing Types

• Alpha Testing: Conducted at the developer’s site by selected users.

• Beta Testing: Released to a broader group of users for real-world testing.

• Acceptance Testing: Final evaluation to determine if the software is ready to be deployed.

Key Points

• Effective testing strategies should aim to discover defects through prior experience and include automated tests wherever possible.

• Techniques like test-first development and scenario testing are beneficial in creating robust test cases.