public void TestNotes()
{
var date = new DateTime(2018, 10, 12);
var notepad = new Notepad();
notepad.Add(date, "text1");
notepad.Add(date, "text2");
var date1 = new DateTime(2018, 12, 25);
notepad.Add(date1, "text3");
Assert.AreEqual(notepad.GetNotes(date).Count, 2);
Assert.AreNotEqual(notepad.GetNotes(date1).Count, 2);
Assert.AreEqual(notepad.GetNotes(date)[0].Text, "text1");
Assert.AreEqual(notepad.GetNotes(date)[1].Text, "text2");
}