public async Task TestRetrieveLocalFileStreamFileNameInvalid()
        {
            // Arrange
            const string fileName = "invalid.pdf";

            var localFileService = new LocalFileService();

            // Act
            var result =
                await localFileService.RetrieveLocalFileStream(fileName);

            // Assert
            Assert.Null(result);
        }
        public async Task TestRetrieveLocalFileStreamFileNameValid()
        {
            // Arrange
            const string fileName = "resume.pdf";

            var localFileService = new LocalFileService();

            // Act
            var result =
                await localFileService.RetrieveLocalFileStream(fileName);

            // Assert
            Assert.NotNull(result);
            Assert.IsAssignableFrom <FileStream>(result);
        }