I have 2 methods is the base abstract class:

public abstract class BaseHttpService
{
......
        protected async Task<T> Post<T>(string url, object? payload, CancellationToken cancellationToken)
        {
            if (string.IsNullOrWhiteSpace(url))
                throw new ArgumentNullException(nameof(url));

            url = $"{_baseUrl}/{url}/";

            return await Send<T>(CreateMessage(url, payload, HttpMethod.Post), cancellationToken);
        }

        protected async Task Post(string url, object? payload, CancellationToken cancellationToken)
        {
            if (string.IsNullOrWhiteSpace(url))
                throw new ArgumentNullException(nameof(url));

            url = $"{_baseUrl}/{url}/";

            await Send(CreateMessage(url, payload, HttpMethod.Post), cancellationToken);
        }
......
}

and a subclass inheriting from this base class:

public class HttpGovPayService : BaseHttpService, IHttpGovPayService
{

.................
public async Task<GovPayResponseDto> InitiatePaymentAsync(GovPayRequestDto paymentRequestDto, CancellationToken cancellationToken)
{
    if (_bearerToken != null)
    {
        SetBearerToken(_bearerToken); // Set the bearer token
    }
    else
    {
        throw new InvalidOperationException(ExceptionMessages.BearerTokenNull);
    }

    var url = UrlConstants.GovPayInitiatePayment;
    try
    {
        // Use the retry policy when calling the Post method
        return await _retryPolicy.ExecuteAsync(async () =>
        {
            return await Post<GovPayResponseDto>(url, paymentRequestDto, cancellationToken);
        });
    }
    catch (Exception ex)
    {
        throw new Exception(ExceptionMessages.ErrorInitiatingPayment, ex);
    }
}
....................
}

Now while testing the retry mechanism, I’m setting up the Post method but keep getting “Sequence contains more than one matching element” and that is because Moq is not able distinguish between Post<T> and Post methods. Both have the same signature but one is not generic. Is there any way to fix this? I should not be changing the code because the tests can’t be created so interested to know if there is anything I can change in the tests. The test snippet is below:

var service = new Mock<HttpGovPayService>(
            _httpContextAccessorMock.Object,
            _httpClientFactoryMock.Object,
            _configMock.Object
        )
        {
            CallBase = true // Use actual implementation for non-mocked methods
        };


        service.Protected()
               .Setup<Task<GovPayResponseDto>>("Post", ItExpr.IsAny<string>(),
               ItExpr.IsAny<GovPayRequestDto>(),
               ItExpr.IsAny<CancellationToken>())
               .Callback(() => postMethodCallCount++)
               .Returns(() =>
               {
                   if (postMethodCallCount < 3)
                   {
                       throw mockException; // Throw exception on the first two calls
                   }
                   Task.FromResult(mockResponse);  // Return mockResponse on the third call
               });