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Fitness Test using Net Arch Test in ASP.NET WEB API

Fitness Test using Net Arch Test in ASP.NET WEB API


18 Articles


In this article, let's learn about Fitness Test using NetArchTest in WebAPI in ASP.NET Core.

Note: If you have not done so already, I recommend you read the article on Request Endpoint Response (REPR) pattern in ASP.NET WEB API.

Table of Contents

  1. Introduction
  2. Why Fitness Test ?
  3. What is Fitness Test ?
  4. Implementing Fitness Test
  5. Advantages
  6. Summary


In the realm of software development, maintaining a robust and consistent architecture is paramount. As projects expand, ensuring that the structural integrity of the codebase remains intact becomes increasingly challenging. Even as of writing this I joined a project which was started six months ago with Clean Architecture in mind, but now it's follows a name sake Clean Architecture and the architecture is already eroding. The codebase is riddled with inconsistencies, and the architecture is far from the initial vision. This is because of pressure and deadline and on the other hand new junior developers joining the team. This is a common problem in software development.

This is where fitness test or fitness functions come into play, serving as vigilant gatekeepers, preserving the essence of your software blueprint. In this blog post, we will delve deep into NetArchTest, a powerful tool designed to validate your software's architectural design, exploring its significance, implementation, advantages, and more.

Why Fitness Test ?

Before we explore the intricacies of NetArchTest, it's crucial to understand the 'why' behind its adoption. NetArchTest project allows you create tests that enforce conventions for class design, naming and dependency in .Net code bases. These can be used with any unit test framework and incorporated into a build pipeline. It uses a fluid API that allows you to string together readable rules that can be used in test assertions.

There are plenty of static analysis tools that can evaluate application structure, but they are aimed more at enforcing generic best practice rather than application-specific conventions. The better tools in this space can be press-ganged into creating custom rules for a specific architecture, but the intention here is to incorporate rules into a test suite and create a self-testing architecture.

Software architecture, akin to a well-thought-out blueprint, is essential for a robust system. However, as deadlines loom and pressure mounts, corners might be cut, leading to architectural erosion. NetArchTest acts as a safeguard, ensuring that your architecture doesn't crumble under the weight of compromises. By automating the verification process, it guarantees that your software adheres to the predefined architectural patterns and rules, even amidst rapid development cycles.

What is Fitness Test ?

NetArchTest is a sophisticated library that empowers developers to write fitness tests effortlessly. By leveraging NetArchTest, developers can enforce architectural rules and validate design decisions. The library scans the imported namespaces of your types, allowing you to define both positive and negative conditions for your architecture. Whether you're aiming to enforce dependencies between layers, validate design rules, or maintain design integrity, NetArchTest provides a simple and effective mechanism to achieve these goals.

Implementing Fitness Test

Implementing NetArchTest in your project is seamless. Start by creating a new test project within your development environment. Then, install the NetArchTest.Rules NuGet package, which equips you with the necessary boilerplate code to initiate your tests. The library's core revolves around the Types class, enabling you to load and filter types based on various criteria. Once your types are selected, you can define rules using Should or ShouldNot conditions, ensuring that your architecture aligns with your predefined specifications.

Code Sample - Fitness Test to Enforce REPR Pattern in Endpoints

Code Sample - Fitness Test to Enforce Clean Architecture

Code Sample - Fitness Test to Enforce rules for Commands and Queries

Code Sample - Fitness Test to Enforce Encapsulation in Domain Entities

Here are some design rules that you can enforce:

  • Domain entities must be encapsulated
  • Services must be internal
  • Entities and Value objects must be sealed
  • Controllers can't depend on repositories directly
  • Command (or query) handlers must follow a naming convention


The advantages of Architecture tests are as follows,

  • Maintain Design Integrity: NetArchTest acts as a guardian, preserving the consistent design and structure of your software as it evolves over time. It prevents architectural drift, ensuring that your initial vision remains intact.
  • Early Issue Detection: By catching architectural discrepancies early in the development process, NetArchTest prevents potential complications that might arise due to structural flaws. Early detection translates to easier debugging and resolution.
  • Improved Collaboration: Clear architectural rules and automated tests make it easier for developers to comprehend the system's design. This shared understanding fosters smoother collaboration, particularly in large teams or when onboarding new members.
  • Quality Assurance: A robust architecture is the cornerstone of high-quality software. NetArchTest contributes significantly to the overall quality and reliability of your software by validating structural decisions and enforcing design rules.


In essence, NetArchTest emerges as a proactive measure, ensuring that the backbone of your software remains resilient and consistent. By automating the verification of architectural patterns and design rules, it not only saves time but also prevents potential headaches in the long run. As software projects grow in complexity, embracing tools like NetArchTest becomes essential, safeguarding your architectural vision and bolstering the reliability of your software systems. So, the next time you embark on a development journey, consider NetArchTest as your loyal sentinel, guarding your software's architectural integrity with unwavering vigilance.

  • Webapi
  • Architecture Test
  • Fitness Functions
  • Fitness Test
  • NetArchTest