Extension methods (here: ServiceProviderServiceExtensions.GetRequiredService) may not be used in setup / verification expressions.

[akshay-zz]

Facing this issue when mocking GetRequiredService
Actual function

private readonly IServiceScopeFactory _provider;
using var scope = _provider.CreateScope();
var queueRepo = scope.ServiceProvider.GetRequiredService<IQueuedMailRepository>();
await queueRepo.Remove(queueEmailDetail.Id);

How I'm trying to mock the injection while testing.

var mockServiceFactory = new Mock<IServiceScopeFactory>();

var mockServiceProvider = new Mock<IServiceProvider>();
var mockServiceScope = new Mock<IServiceScope>();
var mockRepo = new Mock<IQueuedMailRepository>();

mockServiceFactory.Setup(x => x.CreateScope()).Returns(mockServiceScope.Object);
mockServiceScope.Setup(x => x.ServiceProvider).Returns(mockServiceProvider.Object);
mockServiceProvider.Setup(x => x.GetRequiredService<IQueuedMailRepository>()).Returns(mockRepo.Object);
// OR
mockServiceProvider.Setup(x => x.GetRequiredService(typeof(IQueuedMailRepository))).Returns(mockRepo.Object);

Getting following error at last line of mock at run time

Message: 
    System.NotSupportedException : Unsupported expression: x => x.GetRequiredService(Mailer.DataAccess.Contracts.IQueuedMailRepository)
    Extension methods (here: ServiceProviderServiceExtensions.GetRequiredService) may not be used in setup / verification expressions.

[stakx]

Yep, Moq doesn't support setting up extension methods, and there is nothing we can do to change that. You can only set up & verify overridable methods.