Azure Functions DependencyRegistrationChecker

DependencyRegistrationChecker.cs

using System;
using System.Collections.Generic;
using System.Linq;
using FluentAssertions;
using Microsoft.Azure.Functions.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection;
using Moq;
using Xunit;

namespace MyUnitTestProject;

public sealed class DependencyRegistrationChecker
{
    private readonly ServiceProvider _serviceProvider;

    public DependencyRegistrationChecker()
    {
        Startup startup = new(); // reference your function app's namespace for this to work
        IServiceCollection serviceCollection = new ServiceCollection();
        IFunctionsHostBuilder functionsHostBuilder = Mock.Of<IFunctionsHostBuilder>(
            x => x.Services == serviceCollection);
        startup.Configure(functionsHostBuilder);
        _serviceProvider = serviceCollection.BuildServiceProvider();
    }

    [Theory]
    [MemberData(nameof(DataForCheckDependenciesRegistered))]
    public void CheckDependenciesRegistered(Type type)
    {
        IEnumerable<Type> constructorParameterTypes = type
            .GetConstructors()
            .SelectMany(c => c.GetParameters())
            .Select(p => p.ParameterType);

        foreach (Type parameterType in constructorParameterTypes)
        {
            Action act = () => _serviceProvider.GetRequiredService(parameterType);
            act.Should().NotThrow($"ServiceType: {type.Name}");
        }
    }

    public static IEnumerable<object[]> DataForCheckDependenciesRegistered()
    {
        return typeof(Startup).Assembly
            .GetTypes()
            .Where(type => !IsException(type) &&
                           HasCustomConstructor(type))
            .Select(type => new object[] { type });
    }

    private static bool IsException(Type type)
    {
        while (type != null && type.BaseType != typeof(object))
        {
            type = type.BaseType;
        }

        return type == typeof(Exception);
    }

    private static bool HasCustomConstructor(Type type)
    {
        return type.GetConstructors()
            .Any(constructor => constructor.GetParameters().Length > 0);
    }
}

Mentioned here:
Azure/azure-functions-host#6587 (comment)