Test-Driven Development Using Visual Studio and MSTest (4006) — Lesson 3: Refactoring, Isolation, Automation, and Diagnostics

Learning Objectives

• Refactor code and tests while preserving observable behavior
• Use interfaces, fakes, stubs, and isolation concepts for difficult dependencies
• Run, filter, debug, and automate MSTest suites and diagnose failing or flaky tests

Detailed Topics

• Refactor code and tests while preserving observable behavior: Refactor code and tests while preserving observable behavior
• Use interfaces: Use interfaces, fakes, stubs, and isolation concepts for difficult dependencies
• Run: Run, filter, debug, and automate MSTest suites and diagnose failing or flaky tests

Guided Demonstration

1. Review the requirement, environment, dependencies, roles, risks, and expected outcome.
2. Demonstrate the relevant configuration, analysis, code, or administration workflow step by step.
3. Capture settings, outputs, logs, screenshots, calculations, or test evidence.
4. Compare the observed result with the stated acceptance criteria.

Hands-On Activity

Refactor a tested component and isolate one external dependency.

• Document assumptions and the planned sequence before making changes.
• Complete the activity and preserve evidence of normal and exception behavior.
• Record issues, corrective actions, and reusable operational or development notes.

Troubleshooting Focus

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

Validation Checklist

• The requirement and expected outcome are clear.
• The selected configuration, design, query, code, or process is documented.
• Normal, boundary, failure, security, and operational conditions are reviewed.
• The result is supported by evidence and the next improvement is prioritized.

Lesson Outcome

Learners can explain and apply Refactoring, Isolation, Automation, and Diagnostics in a realistic scenario and validate the result with documented evidence.