public void Sum__Empty_Input__Zero()
        {
            var sut      = new InvoiceSum(new InvoiceParseResult[] {});
            var actual   = sut.Sum();
            var expected = new InvoicesSum(0m, 0m);

            Assert.Equal(expected, actual);
        }
        public void Sum__Invoice_With_Error__Correct_Sum()
        {
            var sut = new InvoiceSum(new InvoiceParseResult[]
            {
                new InvoiceParseResult(0, 1, 3),
                new InvoiceParseResult(1, "error"),
            });
            var actual   = sut.Sum();
            var expected = new InvoicesSum(1, 3);

            Assert.Equal(expected, actual);
        }
        public void Sum__Invoice_Amounts__Correct_Sum()
        {
            var sut = new InvoiceSum(new InvoiceParseResult[]
            {
                new InvoiceParseResult(0, 1, 3),
                new InvoiceParseResult(1, 2, 4),
            });
            var actual   = sut.Sum();
            var expected = new InvoicesSum(3, 7);

            Assert.Equal(expected, actual);
        }