FluentIt

FluentIt.cs

using System;
using FluentAssertions;
using Moq;
using Xunit;

namespace TestProject1;

public static class FluentIt
{
    public static TValue IsEquivalentTo<TValue>(TValue expectation)
    {
        Func<TValue, bool> verify = value =>
        {
            value.Should().BeEquivalentTo(expectation);
            return true;
        };

        return It.Is<TValue>(value => verify(value));
    }
}

public class MyTests
{
    private readonly Mock<IUserClient> _userClientMock = new Mock<IUserClient>();
    private readonly Manager _sut;

    public MyTests()
    {
        _sut = new Manager(_userClientMock.Object);
    }

    [Fact]
    public void MyTestCase()
    {
        _sut.TestMethod(); // Act

        var user = new User
        {
            Id = 42,
            First = "stef",
            Last = "test"
        };
        _userClientMock.Verify(uc => uc.AddUser(FluentIt.IsEquivalentTo(user)), Times.Once); // ⭐ Instead of It.Is<User>(u => u.Id == 42, u.First == "stef" && u.Last = "test")
    }
}

public class Manager
{
    private readonly IUserClient _client;

    public Manager(IUserClient client)
    {
        _client = client;
    }

    public void TestMethod()
    {
    }
}

public class IUserClient
{
    public void AddUser(User user)
    {
    }
}

public class User
{
    public int Id { get; set; }

    public string First { get; set; }

    public string Last { get; set; }
}