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Refactoring with C#
Refactoring with C#

Refactoring with C#: Safely improve .NET applications and pay down technical debt with Visual Studio, .NET 8, and C# 12

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Refactoring with C#

Technical Debt, Code Smells, and Refactoring

New software projects start out clean and optimistic, but quickly grow in complexity and difficulty to maintain until the code is difficult to understand, brittle to change, and impossible to test.

If you’ve worked with code for any length of time, chances are you’ve come across code like this. In fact, if you’ve been in development for even a little bit of time, it’s likely you’ve written code you now regret.

It could be that the code is hard to read or understand. Maybe the code is inefficient or prone to errors. Perhaps the code was built under a certain set of business assumptions that later changed. Maybe the code simply no longer conforms to the standards you and your team have agreed to. Whatever the reason, bad code feels like it is practically everywhere in codebases of any significant size or age.

This code litters our software projects and reduces our development speed, causes us to...

Understanding technical debt and legacy code

While computer science education, books, tutorials, and online courses all focus on creating new projects from scratch, the reality is that almost all development jobs you’ll have will center around understanding, maintaining, and expanding pre-existing code that may not meet your current standards.

This pre-existing code is referred to as legacy code. You almost always inherit some amount of legacy code when joining a new project. This can be a large amount of code for pre-existing projects or a smaller set of libraries your code must work with.

There are many different definitions of the term legacy code. One that stands out to me from my readings is Michael C. Feather’s definition, in Working Effectively with Legacy Code, that legacy code is code without tests.

While I like Michael’s definition and believe testing is critically important, as we’ll see in Part 2 of this book, I personally define legacy...

Identifying code smells

So, how do you know whether your code has issues?

How do you know whether food has spoiled, clothing needs to be washed, or a diaper needs changing? It turns out that it just smells bad.

There are some metrics about what constitutes “good” and “bad” code, and we’ll explore them in Chapter 12: Code Analysis in Visual Studio and Chapter 16: Adopting Code Standards. Smelly code can be subjective to some degree or another. A developer who wrote a section of code or frequently modifies that portion of code may find the code to be more tolerable than a developer encountering the code for the first time.

While not all pieces of technical debt are identical, it turns out that many pieces of legacy code share a set of common symptoms.

These symptoms are commonly referred to as “code smells” and can include the following:

  • It’s difficult to understand what it does or why it does it
  • You or people...

Introducing refactoring

Refactoring is one of those words that doesn’t make a lot of sense to newer programmers, but here’s a simple definition:

Refactoring is the act of changing the shape or form of code without changing its functionality or behavior.

There are two key concepts here:

  • The first concept is that refactoring is an effort to improve the maintainability of existing code. Sometimes, restructuring means introducing a new variable, method, or class. Other times, refactoring simply changes how individual lines of code are arranged or which language features are used. Even something as simple as renaming a variable could be considered a small act of refactoring.
  • The second concept in this definition is that refactoring does not alter the behavior of the code in question. Refactoring is a structural change done to bring some piece of technical merit without altering the existing behavior of your code. If a method typically returned a certain value...

Case study – Cloudy Skies Airlines

The rest of this book will follow code examples from an airline called Cloudy Skies Airlines, or Cloudy Skies for short. Through these examples, we should be able to see how technical debt and refactoring can apply to a “real” organization and its software.

Note

Cloudy Skies is a fictitious airline company created for this book for teaching purposes only. Any resemblance to any real company is purely coincidental. Additionally, I have never worked in aviation, so the code examples presented in the book are likely significantly different from actual software systems used in the industry.

Cloudy Skies is an airline that’s been around for the past 50 years and currently operates a little over 500 jets in its fleet, serving around 70 cities in its region.

Twenty years ago, the airline made a major move and started replacing its aging software systems with custom in-house applications built by its development team...

Summary

Legacy code is an unavoidable byproduct of the forces of time and constant change that are present in software development projects. This legacy code becomes a breeding ground for technical debt, which threatens our productivity as developers and the quality of our software.

While technical debt can arise due to a number of reasons, refactoring is the cure. Refactoring reworks existing code into a more maintainable and less risky form, reducing our technical debt and helping us control our legacy code.

The more you understand the causes and effects of technical debt in your code, the better you’ll find yourself equipped to explain technical debt to others in your organization, advocate for refactoring, and avoid things that cause your code to decline in effectiveness over time.

In the next chapter, we’ll explore refactoring in more depth by walking through a set of targeted changes to improve a piece of sample code from the Cloudy Skies Airlines codebase...

Questions

  1. What is the difference between technical debt and legacy code?
  2. What are some causes of technical debt?
  3. What are some of the effects of technical debt?
  4. Is it possible to avoid technical debt?
  5. Is it possible to get to a point where your code cannot be refactored further?

Further reading

You can find more information about technical debt, legacy code, and refactoring at the following URLs:

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Key benefits

  • Apply a wide range of refactoring techniques using the latest tools and features of C#
  • Discover ways to safely improve your code using tests, Roslyn analyzers, and AI assistance
  • Find ways of communicating technical debt and improving your code in agile and enterprise settings
  • Purchase of the print or Kindle book includes a free PDF eBook

Description

Software projects start as brand-new greenfield projects, but invariably become muddied in technical debt far sooner than you’d expect. In Refactoring with C#, you'll explore what technical debt is and how it arises before walking through the process of safely refactoring C# code using modern tooling in Visual Studio and more recent C# language features using C# 12 and .NET 8. This book, written by a Microsoft MVP, will guide you through the process of refactoring safely through advanced unit testing with XUnit and libraries like Moq, Snapper, and Scientist .NET. You'll explore maintainable code through SOLID principles and defensive coding techniques made possible in newer versions of C#. You'll also find out how to run code analysis and write custom Roslyn analyzers to detect and resolve issues unique to your code. The nature of coding is changing, and you'll explore how to use AI with the GitHub Copilot Chat to refactor, test, document, and generate code before ending with a discussion about communicating technical debt to leadership and getting organizational buy-in to refactor your code in enterprise organizations and in agile teams. By the end of this book, you'll understand the nature of refactoring and see how you can safely, effectively, and repeatably pay down the technical debt in your application while adding value to your business.

Who is this book for?

This book is for any developer familiar with C# who wants to improve the code they work with on a day-to-day basis. While this book will be most beneficial to new developers with only a year or two of experience, even senior engineers and engineering managers can make the most of this book by exploring not just the process of refactoring, but advanced techniques with libraries like Moq, Snapper, Scientist .NET, and writing custom Roslyn analyzers.

What you will learn

  • Understand technical debt, its causes and effects, and ways to prevent it
  • Explore different ways of refactoring classes, methods, and lines of code
  • Discover how to write effective unit tests supported by libraries such as Moq
  • Understand SOLID principles and factors that lead to maintainable code
  • Use AI to analyze, improve, and test code with the GitHub Copilot Chat
  • Apply code analysis and custom Roslyn analyzers to ensure that code stays clean
  • Communicate tech debt and code standards successfully in agile teams

Product Details

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Publication date : Nov 24, 2023
Length: 434 pages
Edition : 1st
Language : English
ISBN-13 : 9781835089989
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Product Details

Publication date : Nov 24, 2023
Length: 434 pages
Edition : 1st
Language : English
ISBN-13 : 9781835089989
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Table of Contents

23 Chapters
Part 1: Refactoring with C# in Visual Studio Chevron down icon Chevron up icon
Chapter 1: Technical Debt, Code Smells, and Refactoring Chevron down icon Chevron up icon
Chapter 2: Introduction to Refactoring Chevron down icon Chevron up icon
Chapter 3: Refactoring Code Flow and Iteration Chevron down icon Chevron up icon
Chapter 4: Refactoring at the Method Level Chevron down icon Chevron up icon
Chapter 5: Object-Oriented Refactoring Chevron down icon Chevron up icon
Part 2: Refactoring Safely Chevron down icon Chevron up icon
Chapter 6: Unit Testing Chevron down icon Chevron up icon
Chapter 7: Test-Driven Development Chevron down icon Chevron up icon
Chapter 8: Avoiding Code Anti-Patterns with SOLID Chevron down icon Chevron up icon
Chapter 9: Advanced Unit Testing Chevron down icon Chevron up icon
Chapter 10: Defensive Coding Techniques Chevron down icon Chevron up icon
Part 3: Advanced Refactoring with AI and Code Analysis Chevron down icon Chevron up icon
Chapter 11: AI-Assisted Refactoring with GitHub Copilot Chevron down icon Chevron up icon
Chapter 12: Code Analysis in Visual Studio Chevron down icon Chevron up icon
Chapter 13: Creating a Roslyn Analyzer Chevron down icon Chevron up icon
Chapter 14: Refactoring Code with Roslyn Analyzers Chevron down icon Chevron up icon
Part 4: Refactoring in the Enterprise Chevron down icon Chevron up icon
Chapter 15: Communicating Technical Debt Chevron down icon Chevron up icon
Chapter 16: Adopting Code Standards Chevron down icon Chevron up icon
Chapter 17: Agile Refactoring Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon
Other Books You May Enjoy Chevron down icon Chevron up icon

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N/A Apr 04, 2024
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christophe Jun 21, 2024
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Hello, easy to read, easy to follow for all developers -> junior or with more experience. I like this type of book with too much example and solution..Just one thing, there is some question but where is the response ? thanks and good continuation
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Alvin Ashcraft Nov 24, 2023
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I received an early copy of Matt Eland's book and was able to read most of it over the last two weeks. I recommend this book to .NET developers with all levels of experience.If you're new to .NET, the early chapters provide all the basics of different refactoring techniques. The TDD chapter is also a great kick-start to the test-first approach to coding with .NET.If you're an experienced .NET developer, you may skim through some of the early chapters (and still pick up some useful information - always be learning). The chapter on leveraging AI for refactoring is timely, and Matt's AI knowledge really shines through here. The chapters on Roslyn will appeal to newbies and seasoned developers alike. Everyone should try creating their own refactorings with the Roslyn APIs. It's a great way to help understand the compiler that most .NET devs take for granted.This book has a wonderful balance of coding instructions and patters & practices guidance.
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James O. Jan 30, 2024
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It isn’t just that this book addresses every aspect of rehabilitating a .NET codebase. Matt succinctly informs us how to communicate on, plan for and tackle tech debt in any .NET enterprise application. Developers of any level of experience will find value here. If unstable, unreliable and unreadable code is a crime, then Matt Eland is the programming Batman!
Amazon Verified review Amazon
Brian L. Gorman Nov 27, 2023
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If you are looking to hone your craft and level up your development skills with C#, or you are recently out of a coding bootcamp or graduating with a college degree and want to learn skills and concepts to set yourself apart from others, this book should be on your "must haves" list. This book could also be the thing that helps you as you move from a "junior" to a "senior" level developer.Matt has organized this book well, taking you through a system where there are problems that mimic the problems you will encounter in the real world. You then get to see how to use the default tools to refactor your code, as well as gain an understanding as to why the refactoring has made your code better. This system is consistent through the book, so you'll want to take it from the ground up and follow through to see the full transition of the software.There are many things that trip developers up on a day-to-day basis and they are captured in this book, whether they are basic problems or complex issues. Seasoned developers may find a couple of the concepts all too familiar as you walk through the book but there are some really great additional tools that even veterans may not have heard about that you will want to put into your toolbox.As a trainer of developers, I will be recommending this book heavily to my students, both for the content it offers and the overall comprehension it will provide on some of the tricky pitfalls developers encounter.
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