public void DayStartTest()
{
Assert.Equal(TimeTool.DayStart(testDate).Year, testDate.Year);
Assert.Equal(TimeTool.DayStart(testDate).Month, testDate.Month);
Assert.Equal(TimeTool.DayStart(testDate).Day, testDate.Day);
Assert.Equal(0, TimeTool.DayStart(testDate).Hour);
Assert.Equal(0, TimeTool.DayStart(testDate).Minute);
Assert.Equal(0, TimeTool.DayStart(testDate).Second);
Assert.Equal(0, TimeTool.DayStart(testDate).Millisecond);
} // DayStartTest