Reputation: 12423

Unable to find testhost.dll. Please publish your test project and retry

I have a simple dotnet core class library with a single XUnit test method:

TestLib.csproj:
<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.NET.Test.SDK" Version="15.9.0" />
    <PackageReference Include="xunit" Version="2.4.1" />
    <PackageReference Include="xunit.runner.console" Version="2.4.1">
      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
      <PrivateAssets>all</PrivateAssets>
    </PackageReference>
    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1">
      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
      <PrivateAssets>all</PrivateAssets>
    </PackageReference>
    <PackageReference Include="xunit.runners" Version="2.0.0" />
  </ItemGroup>

</Project>

BasicTest.cs:
using Xunit;

namespace TestLib
{
    public class BasicTest
    {
        [Fact(DisplayName = "Basic unit test")]
        [Trait("Category", "unit")]
        public void TestStringHelper()
        {
            var sut = "sut";
            var verify = "sut";

            Assert.Equal(sut, verify);
        }
    }
}

If I enter the project on the CLI and type dotnet build the project builds. If I type dotnet test I get this:

C:\git\Testing\TestLib> dotnet test
C:\git\Testing\TestLib\TestLib.csproj : warning NU1701: Package 'xunit.runner.visualstudio 2.4.1' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.
Build started, please wait...
C:\git\Testing\TestLib\TestLib.csproj : warning NU1701: Package 'xunit.runner.visualstudio 2.4.1' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.
Build completed.

Test run for C:\git\Testing\TestLib\bin\Debug\netstandard2.0\TestLib.dll(.NETStandard,Version=v2.0)
Microsoft (R) Test Execution Command Line Tool Version 16.0.0-preview-20181205-02
Copyright (c) Microsoft Corporation.  All rights reserved.

Starting test execution, please wait...
Unable to find C:\git\Testing\TestLib\bin\Debug\netstandard2.0\testhost.dll. Please publish your test project and retry.

Test Run Aborted.

What do I need to change to get the test to run?

If it helps, VS Code is not displaying the tests in its test explorer, either.

Upvotes: 248

Answers (30)

Douglas Hahn

Reputation: 61

After trying all the items listed here, I found that my base class was:

class GenerateNewToken

and it should have been

public class GenerateNewToken

Upvotes: 0

Alon Albahari

Reputation: 151

In my case the issue was somehow related to the installed packages. The thing is that I switched between different branches locally and some have some different packages versions.

I had to clean nuget cache and use dotnet restore to get everything back in order.

Upvotes: 0

Adalberto R.N.

Reputation: 1

I added this code in csproj test file and worked

>  <PackageReference Include="coverlet.collector" Version="3.0.2" />
> <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">
> <IncludeAssets>runtime; build; native; contentfiles; analyzers;
> buildtransitive</IncludeAssets>  <PrivateAssets>all</PrivateAssets>
> </PackageReference>

Upvotes: 0

Thierry Brémard

Reputation: 899

Thanks! solved the issue of my testing project targeting netcore3.1

projects installed:

Upvotes: -1

Ognyan Dimitrov

Reputation: 6251

As of today 18.05.2023 with VS 2022 you have to install the following in addition to xunit because otherwise VS will not be able to detect the tests.

Microsoft.NET.Test.Sdk - this will solve the "TestPlatformException: Could not find testhost"
xunit.runner.visualstudio - this will connect the tests visible to VS runner

Upvotes: 11

Pellet

Reputation: 2437

I was receiving the error due to multiple dlls being picked up by the filter instead of just the one dll which contained the tests.

Upvotes: 0

vmb100

Reputation: 127

Restart Visual Studio and do a rebuild. Visual Studio seems to get confused sometimes after switching branches.

Upvotes: 0

Estifanos Bireda

Reputation: 31

In my case Microsoft.NET.Test.Sdk was already installed, I had to reinstall it on Nuget Package Manager and the issue got fixed.

Upvotes: 0

Furki4_4

Reputation: 9

I downloaded .Net.Test.SDK and .Testplatform.TestHost via Nuget to my project but test kept not working. xunit.runner.visualstudio did the trick.

Upvotes: -2

tmndungu

Reputation: 358

I was using .NET Core Framework 6.0 I had to downgrade Microsoft.NET.Test.Sdk from Version 17.1.0 to 16.5.0 to resolve the issue.

Upvotes: 0

ihebiheb

Reputation: 5173

In my case it was a silly mistake. I was referencing xunit also in my source project (not only in my test project)

Deleting the xunit dependency in my source project fixed the problem.

Upvotes: 1

Jpsy

Reputation: 20852

I found 5 factors to be crucial.
(3 of whom were spread throughout the other answers here in mixed variations.)

1 to 4:
Add these Nuget Packages in versions that work for your .NET Core version:

xunit
Microsoft.NET.Test.Sdk
xunit.runner.visualstudio
Microsoft.AspNetCore.Mvc.Testing

5:
Now make sure that Microsoft.NET.Test.Sdk is set to NOT ExcludeAssets. To do so use one of these methods:

In Project Explorer go to Dependencies –> NuGet and find the Sdk package. Right click it and select "Properties". Remove "All" from the field ExcludeAssets.
Alternatively edit your .csproj file and remove ExcludeAssets="All" from the Sdk package entry, if present:

<!-- Bad: -->
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" ExcludeAssets="All" />
<!-- Good: -->
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />

Upvotes: 9

Max Rios

Reputation: 2256

I found a very interesting compatibility issue with a version. I did upgrade just as a normal practice, my code, and I switched to xUnit.runner.visualstudio 2.4.2. It stopped working for .Net Core 3.1. I had to downgrade to 2.4.1 and it started working again.

Additional information after one of my comments.

The package xunit.runner.visualstudio versions <= 2.4.1 includes a reference to Microsoft.NET.Test.Sdk. Later versions don't, so you need to add the reference to your project.

See https://stackoverflow.com/a/63786758/3248302

Upvotes: 21

Blisco

Reputation: 620

This error can occur if you upgrade xunit.runner.visualstudio to a version greater than 2.4.1. Versions up to and including 2.4.1 include a reference to Microsoft.NET.Test.Sdk but later ones don't, so you need to include the reference in your own project.

Interestingly, I found that NCrunch still ran my tests without the additional reference, even though I couldn't run them via the CLI.

Upvotes: 6

Aislan Gelatti Rocha

Reputation: 71

In my case, it was necessary to include a reference to MsTest.TestAdapter module using nuget.

A fresh project with MSTest.TestFramework and Microsoft.Net.Test.Sdk was not enough to run a single unit test.

Noticing in my case I was using a test project targeting .NET framework 4.8 and not .NET core. Although, I strongly believe this fix might apply to that platform as well

Upvotes: 0

Äkwav

Reputation: 91

Had to add Microsoft.TestPlatform.TestHost to get testhost.dll. I found that in this answer https://github.com/dotnet/sdk/issues/7171#issuecomment-261506546

Upvotes: 9

Venu

Reputation: 109

Got this error, when trying to debug a unit test. Below are the steps I tried.

Step 1: Installed Microsof.TestPlatform.TestHost and tried to run the test but no luck.
Step 2: Changed Target framework from .NET Core 2.0 to 2.1 and tried to run the test but no luck.
Step 3: Closed and opened VS2017 and tried to run.

Yay!!! it worked :-) Never miss to try the last step ;-) Hope this helps someone like me.

Upvotes: 1

reim

Reputation: 612

This could also be caused by inadvertently trying to run a non-test project, this usually happens when your test files filter is too wide.

Upvotes: 1

Dev Leader

Reputation: 357

I've encountered this a couple of times and I always forget what's up. Most recently I had:

Class Library -> Targeting .NET Core 3.0
Test Project -> Targeting .NET Core 3.1

Packages for my test project:

Moq -> 4.14.1
xUnit -> 2.4.1
xUnit.Runner.VisualStudio -> 2.4.2

I was seeing:

Unable to find C:\PATH\bin\Debug\netstandard2.0\testhost.dll. Please publish your test project and retry.

And all that I needed to do was add to my test project the missing nuget package: "Microsoft.NET.Test.SDK"

Everything was back to normal at this point.

Upvotes: 16

Shawon Barua

Reputation: 61

If you are running a project by cloning than Solution is to install the Microsoft.NET.Test.Sdk. How to : Tools>Nuget Package Manager>Manage Nuget Packages For Solution...>Search for Microsoft.NET.Test.Sdk and install for your test project.

Upvotes: 0

SaifAli Sanadi

Reputation: 21

same issue i faced for Nunit (.net core 3.1) project . I was using Microsoft.NET.Test.SDK v16.6.1, I downgraded the version to 15.9.0. And it start working

Upvotes: 2

Hakakou

Reputation: 562

If you are targeting netstandard2.0 this will not work. If are using .NET Core. make sure the .csproj contains the following lines:

<TargetFramework>netcoreapp3.0</TargetFramework>

and also contains the package Microsoft.NET.Test.Sdk

Upvotes: 6

Michael Armitage

Reputation: 1672

I was building a netcoreapp2.2 test project and then trying to run dotnet vstest from the bin folder. I noticed that the Microsoft Test DLLs from:

<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.0.1" />

were not being output to my bin folder. Instead of just building, I ran a publish instead which did include the necessary DLLs in the output folder and I was then able to run dotnet vstest from there.

Upvotes: 7

Raj Kumar - rajkrs

Reputation: 1363

If you are using xUnit, make sure your project type is not as netstanderd. As xUnit doesn't support netstanderd, change it to coreapp2.0 or others.

Upvotes: 14

Andreas

Reputation: 6465

In my case, the problem was that I was targeting .NET Core 2.0 and switching to .NET Core 2.1 solved the problem. However I was using Microsoft.NET.Test.SDK v16.4.0 instead of 15.9.0.

Upvotes: 41

SteveHansen

Reputation: 401

This happened to me after updating Microsoft.NET.Test.Sdk from v16.2.0 to v16.4.0 with <TargetFramework>netcoreapp2.0</TargetFramework>. Updating to <TargetFramework>netcoreapp3.0</TargetFramework> resolved the issue for me.

Upvotes: 12

S1r-Lanzelot

Reputation: 2266

Ran into this error, the root cause was the tests were hitting the maximum length for a Windows path (MAX_PATH), which is defined as 260 characters.

Upvotes: 1

Willy Van den Driessche

Reputation: 1759

In my case the problem was that I have an extension project for xunit. There is also a test project to test the extensions. When I ran dotnet test on my solution, my extension project was also picked up as a unit test project (it took me some time to realize this). The reason for this is that it references some xunit packages. One of these xunit packages automatically sets the <IsTestProject>true</IsTestProject> property in you csprj file. This is actually a good thing since 99.99% of the projects that reference xunit are actually unit tests. I could finally solve this by explicitly setting

     <PropertyGroup>
...
        <IsTestProject>false</IsTestProject>
...
      </PropertyGroup>

Manually in my csproj file. Then the problem went away.

Upvotes: 33

Eugene Ihnatsyeu

Reputation: 1585

Fixed it by installing xunit.runner.visualstudio.

Upvotes: 11

Arvind Chourasiya

Reputation: 17382

Installing Microsoft.NET.Test.Sdk package from nuget package manager solved my issue.

Upvotes: 427

Unable to find testhost.dll. Please publish your test project and retry

Answers (30)

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