Generalize .net test dependencies with Directory.Build.props

The Directory.Build.props file offers a lot of interesting features for targeted projects, solution folders, or the entire solution. Lets focus on how we can leverage this to generalize test dependencies and any required configuration in one place.

Test project dependencies tend to be mostly the same across multiple projects and annoyingly can be quite easy to point to different versions and require consolidating. I use the Directory.Build.props at the tests folder to target all test projects, in my case by the suffix .Tests in the name, and apply the generic dependencies in one place.

Example:

<Project>

    <PropertyGroup Condition="$(MSBuildProjectName.EndsWith('.Tests'))">

        <IsPackable>False</IsPackable>

    </PropertyGroup>



    <ItemGroup Condition="$(MSBuildProjectName.EndsWith('.Tests'))">

        <PackageReference Include="Autofac.Extras.Moq" Version="6.1.0" />

        <PackageReference Include="FluentAssertions" Version="6.7.0" />

        <PackageReference Include="FluentAssertions.Analyzers" Version="0.17.2" />

        <PackageReference Include="XUnitToFluentAssertionsAnalyzer" Version="1.0.2">

            <PrivateAssets>all</PrivateAssets>

            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

        </PackageReference>

        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.2.0" />

        <PackageReference Include="xunit" Version="2.4.1" />

        <PackageReference Include="xunit.runner.console" Version="2.4.1">

            <PrivateAssets>all</PrivateAssets>

            <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>

        </PackageReference>

        <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">

            <PrivateAssets>all</PrivateAssets>

            <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>

        </PackageReference>

        <PackageReference Include="AutoFixture" Version="4.17.0" />

        <PackageReference Include="coverlet.collector" Version="3.1.2">

            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

            <PrivateAssets>all</PrivateAssets>

        </PackageReference>

    </ItemGroup>



    <ItemGroup Condition="$(MSBuildProjectName.EndsWith('.Tests'))">

        <ProjectReference Include="..\Sample.Tests.Common\Sample.Tests.Common.csproj" />

    </ItemGroup>

</Project>

In this example, we have all tests projects marked as not being packable, setup of required package references and all tests have a project reference to a common test project that could contain shared things like fixtures, builder, etc. We no longer need to have these in each project and can control what goes in all the tests in one place.

While this was specifically about tests, there are many other use cases. For example we could set things like a copyright and assembly info in one place by targeting all projects, indicating the C# language version at the solution level, etc. Cases like these are often the same for all projects but over time people forget to update some projects or it just becomes tedious to keep up.