Three Attributes of a Successful Test Suite

I learned that the goal of unit testing is “to enable sustainable growth of the software project” (Khorikov, 2020).  

However, I still have several questions—for example, how to design good test cases or how to position unit testing within the software development lifecycle.  

In this article, I’ll explore one of these topics: “What is needed for a good unit test?”

Three Attributes of a Successful Test Suite

Khorikov (2020) describes three essential qualities of a successful test suite:

A successful test suite has the following properties:

• It’s integrated into the development cycle.
• It targets only the most important parts of your code base.
• It provides maximum value with minimum maintenance costs.

Let’s take a deeper look at each of these points.

It’s Integrated into the Development Cycle

I interpret this to mean that Continuous Integration (CI) plays an important role in maintaining a successful test suite.

According to Geeks for Geeks

When developers work in isolation for extended periods and only merge their changes later, it often leads to difficult merges, more conflicts, and the accumulation of hidden bugs.  

Continuous Integration aims to find and fix bugs quickly, streamline the integration of code across teams, improve software quality, and shorten the time to release new features.

In other words, the longer code changes stay separate, the more likely bugs will creep in.  

Frequent integration, supported by running unit tests automatically, helps detect both old and new bugs early—before code is merged into the main branch.

For example, in Visual Studio, you can configure unit tests to run automatically after building a project. Many modern IDEs offer similar features.

It Targets Only the Most Important Parts of Your Codebase

To maximize the effect of unit testing while minimizing cost, developers must constantly ask themselves:  

“Which parts of the code truly require testing?”

Khorikov (2020) advises:

In most applications, the most important part is the business logic—the domain model.

This is a useful guiding principle.  

Of course, what counts as “most important” can change depending on the project context, but generally focusing on business-critical logic ensures that your tests deliver the most value.

It Provides Maximum Value with Minimum Maintenance Costs

As mentioned earlier, the goal is maximum benefit at minimum cost.

If developers try to write unit tests for every tiny behavior, the test suite can grow too large, become chaotic, and eventually unmaintainable.  

Instead, we should aim for a clean, focused suite where maintenance is as simple as possible.

Good tests should:

• Fail for meaningful reasons
• Be easy to understand
• Be easy to update when production code changes

Summary

I learned three key attributes that a successful test suite should have:

• It’s integrated into the development cycle.
• It targets only the most important parts of the codebase.
• It provides maximum value with minimum maintenance costs.

My Issue

Khorikov (2020) sometimes emphasizes that writing better unit tests requires understanding software design patterns.  

While developers who don’t study design patterns may notice bad tests by following best practices, they often struggle to suggest how to redesign them.  

Since I want to write better and more sustainable test cases, I realize that I need to deepen my knowledge of software design patterns as well.

References

• Khorikov, Vladimir. *Unit Testing Principles, Practices, and Patterns*. Manning. Kindle Edition.
• Geeks for Geeks, What is CI/CD?, last updated: April 14, 2025