Object-Oriented Programming in C# (4001) — Lesson 4: Design Quality and Testing

Learning Objectives

• Apply SOLID principles, dependency injection, refactoring, and common patterns
• Create unit tests for object behavior, boundaries, and failure cases
• Review coupling, cohesion, naming, documentation, and maintainability

Detailed Topics

• Apply SOLID principles: Apply SOLID principles, dependency injection, refactoring, and common patterns
• Create unit tests for object behavior: Create unit tests for object behavior, boundaries, and failure cases
• Review coupling: Review coupling, cohesion, naming, documentation, and maintainability

Guided Demonstration

1. Review the requirement, users, data, dependencies, permissions, risks, and expected result.
2. Demonstrate the relevant configuration, development, administration, analysis, or collaboration workflow step by step.
3. Capture settings, outputs, logs, screenshots, calculations, test results, and other useful evidence.
4. Compare the observed result with acceptance criteria and explain any corrective action.

Hands-On Activity

Refactor and test an object-oriented C# application.

• Document assumptions, prerequisites, and the planned sequence before starting.
• Complete the activity and preserve evidence of normal, boundary, and failure behavior.
• Record issues, corrective actions, reusable notes, and the next improvement priority.

Scenario Analysis

• Identify the business or technical decision that must be made.
• Compare valid implementation approaches and their trade-offs.
• Consider security, privacy, accessibility, performance, support, and operational impact.

Troubleshooting Focus

• Separate symptoms from causes and collect evidence before applying a fix.
• Check configuration, data, permissions, dependencies, capacity, connectivity, and recent changes.
• Validate rollback, recovery, ownership, user impact, and business continuity.

Validation Checklist

• The requirement, scope, inputs, and expected outcome are clear.
• The selected design or configuration is documented and follows approved standards.
• Normal, boundary, failure, security, accessibility, and operational conditions are reviewed.
• The result is supported by evidence and the next improvement is prioritized.

Lesson Outcome

Learners can explain and apply Design Quality and Testing in a realistic scenario and validate the result with documented evidence.