RenderComponent.cs

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;
using AngleSharpWrappers;
using Bunit;
using Microsoft.AspNetCore.Components;

namespace ConsoleAppBUnit
{
    class Program
    {
        static void Main(string[] args)
        {
            var x = new X();

            var r = x.RenderComponent<Com>(ComponentParameter.CreateParameter("Age", 42));

            var cut = x.RenderComponent<Com>(c => c.Name == "x", c => c.Age == 42);
        }

        class X : TestComponentBase
        {
            public IRenderedComponent<TComponent> RenderComponent<TComponent>(params Expression<Func<TComponent, object>>[] parameters) where TComponent : class, IComponent
            {
                var componentParameters = new List<ComponentParameter>();
                foreach (var parameter in parameters)
                {
                    if (parameter.Body is UnaryExpression body)
                    {
                        if (body.Operand is BinaryExpression methodBinaryExpression)
                        {
                            if (methodBinaryExpression.Left is MemberExpression left && methodBinaryExpression.Right is ConstantExpression right)
                            {
                                var name = left.Member.Name;
                                var value = right.Value;

                                componentParameters.Add(ComponentParameter.CreateParameter(name, value));
                            }

                        }
                    }
                }

                return base.RenderComponent<TComponent>(componentParameters.ToArray());
            }
        }

        class Com : IComponent
        {
            [Parameter]
            public string Name { get; set; }

            [Parameter]
            public int Age { get; set; }

            public void Attach(RenderHandle renderHandle)
            {
                //throw new NotImplementedException();
            }

            public Task SetParametersAsync(ParameterView parameters)
            {
                return Task.CompletedTask; // throw new NotImplementedException();
            }
        }
    }
}