Do you know the most popular unit and integration testing frameworks for .NET applications?

Last updated by William Liebenberg 8 months ago.See history

There are three main frameworks for unit testing. The good news is that they are all acceptable choices:

  • They all have test runner packages for running tests directly from Visual Studio
  • They all have console-based runners that can run tests as part of a CI/CD pipeline
  • They differ slightly in syntax and feature set

xUnit.net – Recommended

xUnit.net is a newer framework – written by the original creator of NUnit v2 to create a more opinionated and restrictive framework to encourage TDD best practice. For example, when running xUnit tests, the class containing the test methods is instantiated separately for each test so that tests cannot share data and can run in parallel.

xUnit.net is currently the most popular framework - and is even used by the .NET Core team.

However, one should note that XUnit is still using the old Assert standard, and should be augmented by a better assertion library, like FluentAssertions or Shouldly.

xUnit.net is the default choice for .NET Core web applications and APIs at SSW.

NUnit

The NUnit project deserves recognition for being the first powerful and open-source unit test framework for the .NET universe – and it’s still a solid choice today.

NUnit has undergone large changes in the last 10 years with its NUnit3 version. The most notable is the Assert Constraints, which is a built-in Fluent Assertion library, allowing you to write readable asserts like Assert.That(x, Is.EqualTo(42).Within(0.1)). It has also adopted the lifetime scopes of XUnit, but you can choose which one to use.

NUnit differs from XUnit in being more flexible and more adaptable versus XUnit being more restrictive and opinionated.

Because NUnit has an open-source .NET UI control for running tests, NUnit is still SSW’s preferred choice for embedding unit tests and a runner UI inside a Windows application.

MSTest

MSTest is Microsoft's testing framework. In the past this was a poor choice as although this was the easiest framework to run from Visual Studio, it was extremely difficult to automate these tests from CI/CD build servers. These problems have been completely solved with .NET Core but for most C# developers this is “too little, too late” and the other unit testing frameworks are now more popular.

Respawn

Respawn is a lightweight utility for cleaning up a database to a known state before running integration tests. It is specifically designed for .NET developers who use C# for testing purposes. By intelligently deleting only the data that has changed, Respawn can dramatically reduce the time it takes to reset a test database to its initial state, making it an efficient tool for improving the speed and reliability of integration tests. Respawn supports SQL Server, PostgreSQL, and MySQL databases.

TestContainers for .NET

Testcontainers for .NET! is a library that enables C# .NET developers to create, manage, and dispose of throwaway instances of database systems or other software components within Docker containers for the purpose of automated testing.

It provides a programmatic API to spin up and tear down containers, ensuring a clean and isolated environment for each test run. Testcontainers supports various containers, including databases like SQL Server, PostgreSQL, and MongoDB, as well as other services like Redis, Kafka, and more, making it a versatile tool for integration testing in a .NET environment.

Mixing test frameworks

Dotnet is a flexible ecosystem, and that also applies to the use of test frameworks. There is nothing preventing you from using multiple different test frameworks in the same project. They will coexist with no pain. That way one can get the best from each, and not be locked-in with something that doesn't allow you to do your job efficiently.

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