private void SetupHttpClient(PostCodeValidationResponse mockResponse)
        {
            _fakeMessageHandler = new FakeHttpMessageHandler(new HttpResponseMessage
            {
                StatusCode = HttpStatusCode.OK,
                Content    = new StringContent(JsonConvert.SerializeObject(mockResponse))
            });

            _httpClient = new HttpClient(_fakeMessageHandler);
        }
        public async Task Validate_InvalidPostCode_ReturnsInvalidResult()
        {
            var validApiResponse = new PostCodeValidationResponse
            {
                result = false
            };

            SetupHttpClient(validApiResponse);
            _postCodeValidator = new PostCodeValidator(_httpClient, _config);

            var response = await _postCodeValidator.Validate("postCode");

            Assert.IsFalse(response.result);
        }