CaptchaValidatorTests.cs

    public class CaptchaValidatorTests
    {
        private Mock<FakeHttpMessageHandler> _fakeHttpMessageHandler;
        private HttpClient _httpClient;
        public CaptchaValidatorTests()
        {
            _fakeHttpMessageHandler = new Mock<FakeHttpMessageHandler> { CallBase = true };
            _httpClient = new HttpClient(_fakeHttpMessageHandler.Object);
        }

        [Fact]
        public async Task ValidateCaptchaAsync_ShouldReturn_TheCorrectType()
        {
            //Arrange
            _fakeHttpMessageHandler.Setup(f => f.Send(It.IsAny<HttpRequestMessage>())).Returns(new HttpResponseMessage
            {
                StatusCode = HttpStatusCode.OK,
                Content =new StringContent("{\"success\": false,\"error-codes\": [\"It's a fake error!\",\"It's a fake error\"]}")
            });

            var sut = new CaptchaValidator(_httpClient);

            //Act
            var result = await sut.ValidateCaptchaAsync();

            //Assert
            result.Should().NotBeNull();
            result.Should().BeOfType<CaptchaResponse>();
        }

    }