public void ProcessFromFile_ShouldThrowArgumentNullException_IfFilePathIs(string filePath)
        {
            //  Arrange
            var sut = new ParcelApplication(null, null, null);

            //  Act
            Action act = () => sut.ProcessFromFile(filePath);

            //  Assert
            act.Should().Throw <ArgumentNullException>();
        }
        public void ProcessFromFile_ShouldThrowFileNotFoundException_IfFileCannotBeFound()
        {
            //  Arrange
            var mockFileSystem = new Mock <IFileSystem>();

            mockFileSystem.Setup(x => x.FileExists(It.IsAny <string>())).Returns(false);

            var sut = new ParcelApplication(null, null, mockFileSystem.Object);

            //  Act
            Action act = () => sut.ProcessFromFile("c:\\fakefile.xml");

            //  Assert
            act.Should().Throw <FileNotFoundException>();
        }