Getting Tests Setup Quickly in .NET Core

Testing in .NET Core is extremely easy with xunit but the setup process for those of us outside of Visual Studio can be a bit trickier. In this post I will cover setting up all of the packages and getting a demo test running.

Target audience

The .NET landscape is a big place and there are a lot of ways to do development. This post is targetted at the following people:

• who want to run tests in the same project as their application
• are on .NET Core 1.1
• are using the CLI instead of Visual Studio
  • VS Code as your editor counts as CLI

At the time of publishing, only .NET Core apps are supported for running tests. So, if you want to run tests in your library project it will require a separate project for running tests. I won't be going through that here.

To check your target framework, open your .csproj and look for something similar to this line

<TargetFramework>netcoreapp1.1</TargetFramework>

The important part here is netcoreapp.

Install packages

These are the packages that will get your tests going:

• xunit
• xunit.runner.visualstudio
• microsoft.testplatform.testhost

You can install these by running the following commands

dotnet add package xunit
dotnet add package xunit.runner.visualstudio
dotnet add package microsoft.testplatform.testhost

Now you will need to run a dotnet restore and dotnet build. For safety. I think.

Optional package!

If you like having your tests run on every change, add this to your .csproj

<ItemGroup>
    <DotNetCliToolReference Include="Microsoft.DotNet.Watcher.Tools" Version="1.0.0" />
</ItemGroup>

Do a dotnet restore so that your watcher gets installed. You will now have access to dotnet watch -h.

Ask dotnet not to generate a Program.cs

Prior to creating any tests, we're going to add a line to the csproj file. What it does is avoid an error when tests are run later by asking the test framework to not add a Program.cs. In the csproj file, look for

<PropertyGroup>
  <TargetFramework>netcoreapp1.0</TargetFramework>
	...
</PropertyGroup>

Inside that <PropertyGroup>, add the following line:

<GenerateProgramFile>false</GenerateProgramFile>

I'll be honest, Andrew Lock has done all the hardwork on figuring out what causes an error and why. I definitely suggest you checkout his post: Fixing the error "Program has more than one entry point defined" for console apps containing xUnit tests.

Create a test test

Now lets create a simple test. The file can be placed anywhere as xunit should look for [Fact]s and [Theory]s.

// __tests__/Test.test.cs
using Xunit;

namespace AProjectName.Tests
{
    public class Test
    {
        [Fact]
        public void OneIsEqualToOne()
        {
            Assert.Equal(1, 1);
        }
    }
}

You can learn more abour writing tests from the xunit documentation.

The moment of truth! Hop over to your console and run dotnet test or dotnet watch test. You should see output that looks similar to this:

Build started, please wait...
Build completed.

Test run for D:\AProjectName\bin\Debug\netcoreapp1.1\AProjectName.dll(.NETCoreApp,Version=v1.1)
Microsoft (R) Test Execution Command Line Tool Version 15.0.0.0
Copyright (c) Microsoft Corporation.  All rights reserved.

Starting test execution, please wait...
[xUnit.net 00:00:00.7076855]   Discovering: AProjectName
[xUnit.net 00:00:00.8317487]   Discovered:  AProjectName
[xUnit.net 00:00:00.8899867]   Starting:    AProjectName
[xUnit.net 00:00:01.0408994]   Finished:    AProjectName

Total tests: 1. Passed: 1. Failed: 0. Skipped: 0.
Test Run Successful.
Test execution time: 1.9250 Seconds

Tests are executing!

Finale

As I mentioned earlier, .NET is a big place. Here are a few resources I used to get this post together and so that you can build more complex setups for your projects.

• The dotnet-test documenation
• Developing ASP.NET Core apps using dotnet watch