public void ListSourceClear()
{
tlog.Debug(tag, $"ListSourceClear START");
var para = new TestEnumerable();
var testingTarget = new ListSource(para);
Assert.IsNotNull(testingTarget, "should be not null");
Assert.IsInstanceOf <ListSource>(testingTarget, "should be an instance of testing target class!");
testingTarget.Clear();
Assert.AreEqual(testingTarget.Count, 0, "The ListSouce should be empty after cleared.");
testingTarget.Dispose();
tlog.Debug(tag, $"ListSourceClear END (OK)");
}