public void UpdateItem_AreEqual()
        {
            TestContext.WriteLine(@"--------------------------------------------------------------------------------");
            TestContext.WriteLine($@"{nameof(UpdateItem_AreEqual)} start.");

            var _records = new ObservableCollection <string> {
                "21", "22", "23", "24", "25", "26", "27", "28", "29", "20"
            };
            ArrayRecord _arrayRecord = new ArrayRecord("1", _records);

            _arrayRecord.UpdateItem(0, "99");
            var actual = _arrayRecord.Items[0];

            TestContext.WriteLine($"actual: {actual}");
            var expected = "99";

            TestContext.WriteLine($"expected: {expected}");
            Assert.AreEqual(expected, actual);

            _arrayRecord = new ArrayRecord("1");
            _arrayRecord.UpdateItem(0, "100");
            _arrayRecord.UpdateItem(3, "10");
            actual = _arrayRecord.CalcSum.ToString();
            TestContext.WriteLine($"actual: {actual}");
            expected = "110";
            TestContext.WriteLine($"expected: {expected}");
            Assert.AreEqual(expected, actual);

            TestContext.WriteLine($@"{nameof(UpdateItem_AreEqual)} complete.");
        }
        public void Sum_AreEqual()
        {
            TestContext.WriteLine(@"--------------------------------------------------------------------------------");
            TestContext.WriteLine($@"{nameof(Sum_AreEqual)} start.");

            var _records = new ObservableCollection <string> {
                "21", "22", "23", "24", "25", "26", "27", "28", "29", "20"
            };
            ArrayRecord _arrayRecord = new ArrayRecord("1", _records);
            var         actual       = _arrayRecord.CalcSum;

            TestContext.WriteLine($"actual: {actual}");
            var expected = 245;

            TestContext.WriteLine($"expected: {expected}");
            Assert.AreEqual(expected, actual);

            _arrayRecord = new ArrayRecord("1");
            actual       = _arrayRecord.CalcSum;
            TestContext.WriteLine($"actual: {actual}");
            expected = 0;
            TestContext.WriteLine($"expected: {expected}");
            Assert.AreEqual(expected, actual);

            TestContext.WriteLine($@"{nameof(Sum_AreEqual)} complete.");
        }