Design Patterns Using .NET — Lesson 4: Architecture, Testing, and Pattern Review

Learning Objectives

• Apply layered, clean, hexagonal, CQRS, event-driven, and microservice pattern concepts
• Test pattern-based components using mocks, fakes, and dependency boundaries
• Identify pattern overuse, anti-patterns, technical debt, and refactoring priorities

Detailed Topics

• Apply layered: Apply layered, clean, hexagonal, CQRS, event-driven, and microservice pattern concepts
• Test pattern-based components using mocks: Test pattern-based components using mocks, fakes, and dependency boundaries
• Identify pattern overuse: Identify pattern overuse, anti-patterns, technical debt, and refactoring priorities

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

Review a .NET architecture and produce a pattern-improvement plan.

• 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 Architecture, Testing, and Pattern Review in a realistic scenario and validate the result with documented evidence.