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Libraries

When building a reusable library that defines shared hooks, custom attributes, base classes, or data sources for TUnit, reference TUnit.Core instead of the main TUnit package. The TUnit package configures a project as an executable test suite; TUnit.Core provides all the models and attributes needed for authoring test infrastructure without the test runner wiring.

When to Build a TUnit Library​

  • Shared lifecycle hooks (e.g., database setup, authentication) used across multiple test projects
  • Custom attributes that encapsulate common test metadata or behavior
  • Reusable data sources for parameterized tests
  • Base test classes with standard setup and teardown logic

Example .csproj for a TUnit Library​

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="TUnit.Core" />
  </ItemGroup>

</Project>

This produces a class library (.dll), not an executable.

Example Library Code​

using TUnit.Core;
using static TUnit.Core.HookType;

namespace MyCompany.Testing;

public abstract class DatabaseTestBase
{
    [Before(Test)]
    public async Task ResetDatabase()
    {
        await TestDatabase.ResetAsync();
    }

    [After(Test)]
    public async Task CleanupConnections()
    {
        await TestDatabase.CloseConnectionsAsync();
    }
}

Consuming the Library​

In a test project, reference both TUnit (for the runner) and the library project:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
    <OutputType>Exe</OutputType>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="TUnit" />
    <ProjectReference Include="..\MyCompany.Testing\MyCompany.Testing.csproj" />
  </ItemGroup>

</Project>

Tests then inherit from the shared base class:

using MyCompany.Testing;

public class OrderTests : DatabaseTestBase
{
    [Test]
    public async Task Order_Is_Created_Successfully()
    {
        var order = await OrderService.CreateAsync("item-1");

        await Assert.That(order.Id).IsNotNull();
    }
}