public async void Replace_WhenSelectorIsValid_ReturnsReplacedHtmlWith200StatusCode()
        {
            //Arrange
            var html = @"<body>
                <div>
                <p>John M</p>
                <p>Kelly T</p>
                <p>Ryan S</p>
                </div>
            </body>";

            var htmlParserService = new Mock <IHtmlParserService>();

            htmlParserService.Setup(s => s.ReplacePeopleNames(It.IsAny <string>())).ReturnsAsync(html);

            var htmlParserController = new HtmlParserController(htmlParserService.Object);

            //Act
            var response = await htmlParserController.ReplacePeopleNamesRandomly("//div//p");

            var contentResult = response as ContentResult;

            //Assert
            Assert.NotNull(contentResult);
            Assert.Equal(StatusCodes.Status200OK, contentResult.StatusCode);
        }
        public async void Replace_WhenSelectorIsEmpty_Returns400BadRequest()
        {
            //Arrange
            var htmlParserService    = new Mock <IHtmlParserService>();
            var htmlParserController = new HtmlParserController(htmlParserService.Object);

            //Act
            var response = await htmlParserController.ReplacePeopleNamesRandomly("");

            var badRequestResult = response as BadRequestResult;

            //Assert
            Assert.NotNull(badRequestResult);
            Assert.Equal(StatusCodes.Status400BadRequest, badRequestResult.StatusCode);
        }