A C# attribute deriving from AutoDataAttribute in AutoFixture.NUnit3 that can be customized per test.

SmartAutoDataAttribute.cs

public class SmartAutoDataAttribute : AutoDataAttribute
{
    public SmartAutoDataAttribute() : base(() => CreateFixture(null)) { }

    public SmartAutoDataAttribute(Type type, string methodName) : base(CreateFixtureWithMethod(type, methodName)) { }

    private static Func<IFixture> CreateFixtureWithMethod(Type type, string methodName)
    {
        if (type == null)
        {
            throw new ArgumentNullException(nameof(type));
        }

        if (methodName == null)
        {
            throw new ArgumentNullException(nameof(methodName));
        }

        var method = (Action<IFixture>)Delegate.CreateDelegate(typeof(Action<IFixture>), type, methodName);

        if (method == null)
        {
            throw new ArgumentException($"Method '{methodName}' not found in {type.Name}.", methodName);
        }

        return () => CreateFixture(method);
    }

    private static IFixture CreateFixture(Action<IFixture> method)
    {
        var fixture = new Fixture();

        fixture.Customize(new AutoMoqCustomization
        {
            ConfigureMembers = true,
            GenerateDelegates = true
        });

        method?.Invoke(fixture);

        return fixture;
    }
}

SmartDataAutoTests.csproj

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

  <PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>

    <IsPackable>false</IsPackable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="AutoFixture" Version="4.8.0" />
    <PackageReference Include="AutoFixture.AutoMoq" Version="4.8.0" />
    <PackageReference Include="AutoFixture.NUnit3" Version="4.8.0" />
    <PackageReference Include="Moq" Version="4.10.1" />
    <PackageReference Include="nunit" Version="3.11.0" />
    <PackageReference Include="NUnit3TestAdapter" Version="3.11.0" />
    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.9.0" />
  </ItemGroup>

</Project>

UnitTest1.cs

public class Tests
{
    [Test, SmartAutoData(typeof(Tests), nameof(Test1Configuration))]
    public void Test1(string test)
    {
        Assert.That(test, Is.EqualTo("Hello World"));
    }

    static void Test1Configuration(IFixture fixture)
    {
        fixture.Register(() => "Hello World");
    }

    [Test, SmartAutoData]
    public void Test2(string test)
    {
        Assert.That(test, Is.Not.EqualTo("Hello World"));
        Assert.That(test, Is.Not.EqualTo("Foo Bar"));
    }

    [Test, SmartAutoData(typeof(Tests), nameof(Test3Configuration))]
    public void Test3(string test)
    {
        Assert.That(test, Is.EqualTo("Foo Bar"));
    }

    static void Test3Configuration(IFixture fixture)
    {
        fixture.Register(() => "Foo Bar");
    }
}