Mock concrete class

AutoDataAttributes.cs

public class AutoMockDataAttribute : AutoDataAttribute
{
    public AutoMockDataAttribute()
        : base(() => new Fixture().Customize(new AutoMoqCustomization()))
    {
    }
}

public class InlineAutoMockDataAttribute : InlineAutoDataAttribute
{
    public InlineAutoMockDataAttribute(params object[] values)
        : base(new AutoMockDataAttribute(), values)
    {
    }
}

MockAttribute.cs

[AttributeUsage(AttributeTargets.Parameter)]
public class MockAttribute : Attribute, IParameterCustomizationSource
{
    public ICustomization GetCustomization(ParameterInfo parameter)
    {
        return new MockedParameterCustomization(parameter);
    }

    private class MockedParameterCustomization : ICustomization
    {
        private readonly ParameterInfo parameter;

        public MockedParameterCustomization(ParameterInfo parameter)
        {
            this.parameter = parameter;
        }

        public void Customize(IFixture fixture)
        {
            var parameterType = parameter.ParameterType;
            if (parameterType.IsGenericType && parameterType.GetGenericTypeDefinition().Equals(typeof(Mock<>)))
            {
                var genericArgument = parameterType.GetGenericArguments().Single();
                fixture.Customizations.Add(new MockRelay(new ExactTypeSpecification(genericArgument)));
                return;
            }

            fixture.Customizations.Add(new MockRelay(new ExactTypeSpecification(parameterType)));
        }
    }
}

UnitTests.cs

public class UnitTests
{
    [Theory]
    [InlineAutoMockData(5)]
    public void Foo(int a, [Frozen][Mock]Mock<TimeProvider> providerMock, Wrapper<TimeProvider> wrapper)
    {
        Assert.Same(providerMock.Object, wrapper.Value);
        Assert.Equal(5, a);
    }
}

Wrapper.cs

public class Wrapper<T>
{
    public Wrapper(T value)
    {
        Value = value;
    }

    public T Value { get; }
}