System Testing

Overview

• Definition: Third test level in development life cycle.
• Scope: Tests the behavior of the whole system or software as defined by scope.
• Integration: Tests after all modules are integrated.

Purpose

• Defect Detection: Aim to find as many defects as possible.
• Tester: Conducted by specialist testers, forming an independent test team.
• Independence: Developers are not involved in system testing.

Environment

• Similarity to Production: System test environment should be very close to production to minimize risk of environment-specific failures.
• Readiness: The software at this phase has almost all requirements implemented.

Requirements Tested

• Functional: Use black box techniques (specification-based) to test functional requirements.
• Non-Functional: Includes performance and load testing to see system response under high load.
• Thoroughness: White box techniques to assess coverage (decision coverage, statement coverage).

Test Case Sources

• Documentation: Software Requirement Specification (SRS).
• Business Processes: Existing business process documentation guides end-to-end scenarios.
• End User Scenarios: How users will interact with the system.
• High-Level System Behavior: Description of system behavior aids in test design.
• Operating System Interaction: Tests based on interactions with different OS (Linux, Windows, etc.).
• Risk Assessment: Focus on critical modules like checkout, refund for e-commerce based on risk.

Designing Test Cases

• SRS-Based: Design functional test cases from the requirement specification.
• Business Processes: Use to write end-to-end business scenarios.
• User Interactions: Design scenarios based on how users will interact with the system.
• System Behavior: High-level descriptions used for designing test cases.
• OS Interaction: Separate test cases for different operating systems.
• Risk-Based: Identify high-risk modules and focus more test cases there (e.g., checkout, refund in e-commerce).