Unit Test Naming Convention and VS Snippets

05 February 2022 Guus-Beltman

Writing unit tests is important for making robust application code. In this article I will explain why naming conventions are important, show an example with some practical comments and share my Visual Studio snippet (big time-saver).

When writing a unit test it is important to give a good descriptive name for your class and test methods, using a naming convention. The convention that I personally like:

  • Name the class in the form of 'WhenUsing$ClassName$', where $ClassName$ is the application class I want to write tests for.
  • Name the test methods in the form of 'Given_$StateUnderTest$_Expect_$ExpectedBehavior$', where state and behaviour specify the start and end condition of the test.

This naming convention results in very readable sentences in fail messages and a nice structure in Visual Studio:

Example unit test for testing Free Shipping method of PostalService class:

using FluentAssertions;
using Xunit;
namespace Demo
{
    public class WhenUsingPostalService
    {
        [Fact]
        public void Given_OrderAbove50_Expect_FreeShipping()
        {
            //Arrange.
            PostalService postalService = new PostalService();

            //Act.
            bool freeShipping = postalService.FreeShipping(55.0);

            //Assert.
            freeShipping.Should().BeTrue();
        }

    }
}

There are few things I want to point out:

  • I am using FluentAssertions library (line 1, available as NuGet package). This helps me to write asserts in a human readable way on line 17: freeShipping.Should().BeTrue()
  • I am using xUnit (line 2, available as NuGet package) as testing framework here, so I can annotate my tests with [Fact] on line 7.
  • I try to follow the convention Arrange + Act + Assert to structure my tests.

Due to the use of conventions and structure, unit test code are looking much alike. So, this is a great opportunity to create a reusable Code Snippet to save time. With a Code Snippet you configure a shortcut code and when pressing tabs two times to replace it with a complete block of code.

My snippet is using the shortcut xfact and works like this:

You can download the Visual Studio snippet for xUnit test in my Github repository. You can use Code Snippets Manager to import into Visual Studio.

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