Mockup - zero-reflection, compile-time mocking

C# Source Generators for efficient mocking

Demo

Given an interface:

public interface IObjectService
{   
    object ReadWriteProperty { get; set; }

    object SingleArgReturnMethod(object arg);
}

Mock it in your test code:

using Mockup;
using Xunit;

// This will generate mock; use Mock(typeof(IObjectService)) for C# < 11.0
[assembly: Mock<IObjectService>]

namespace Mockup.Tests;

public class ObjectServiceMockTests
{
    [Fact]
    public void TestReadWriteProperty()
    {
        object value = "Value";
        
        var objectService = new ObjectServiceMock()
            .ReadWriteProperty(() => value, v => value = v)
            .Build(); // This will produce IObjectService
        
        // Your test code...
        var result = objectService.ReadWriteProperty; // returns "Value"
    }

    [Fact]
    public void TestSingleArgReturnMethod()
    {
        var objectService = new ObjectServiceMock()
            .SingleArgReturnMethod(v => "Changed" + v)
            .Build(); // This will produce IObjectService

        // Your test code...
        var result = objectService.SingleArgReturnMethod("Value"); // returns "ChangedValue"
    }
}

Installation

Install Mockup via NuGet package: Mockup, Mockup.Analyzers

<PackageReference Include="Mockup" Version="0.5.0" />
<PackageReference Include="Mockup.Analyzers" Version="0.5.0">
    <PrivateAssets>all</PrivateAssets>
    <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
</PackageReference>

Benchmarks

BenchmarkDotNet v0.13.12, macOS Ventura 13.6.6 (22G630) [Darwin 22.6.0]
Intel Core i5-7267U CPU 3.10GHz (Kaby Lake), 1 CPU, 4 logical and 2 physical cores
.NET SDK 8.0.301 [Host]     : .NET 8.0.6 (8.0.624.26715), X64 RyuJIT AVX2

Return string provided by a varialbe:

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Gen2 | Allocated | |------------ |------------:|-----------:|-----------:|-------:|-------:|-------:|----------:| | Mockup | 34.60 ns | 0.599 ns | 0.531 ns | 0.0688 | - | - | 144 B | | Moq | 4,380.75 ns | 58.442 ns | 51.808 ns | 1.8616 | - | - | 3905 B | | NSubstitute | 5,410.08 ns | 105.646 ns | 121.662 ns | 3.7384 | - | - | 7833 B | | FakeItEasy | 5,701.07 ns | 107.159 ns | 114.659 ns | 2.4109 | 0.0153 | 0.0076 | 5057 B |

Return string passed as an argument:

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Gen2 | Allocated | |------------ |-------------:|-------------:|-----------:|-------:|-------:|-------:|----------:| | Mockup | 16.39 ns | 0.392 ns | 0.347 ns | 0.0268 | - | - | 56 B | | Moq | 76,471.38 ns | 1,119.135 ns | 934.529 ns | 4.1504 | 1.2207 | 0.4883 | 9118 B | | NSubstitute | 6,309.30 ns | 115.183 ns | 107.743 ns | 3.7537 | - | - | 7905 B | | FakeItEasy | 6,377.44 ns | 121.293 ns | 129.783 ns | 2.7771 | 0.0305 | 0.0305 | 5861 B |

TODO

This is an early stage, experimental project. The following is not done:

• Mocking generic types
• Custom names for mocks
• Arbitrary namespace for mocks