public void CaclucatesCorrectlyFromValidSizes()
{
IReadOnlyList <PageNumberAndItemNumbers> pages
= PageNumberAndItemNumbers.Calculate(20, 119);
Assert.IsNotNull(pages);
Assert.AreEqual(6, pages.Count);
Assert.AreEqual(119, pages[pages.Count - 1].LastItemNumber);
int lastItemNumber = 0;
for (int i = PageNumberAndSize.FirstPageNumber; i <= pages.Count; i++)
{
int firstItemNumber = lastItemNumber + 1;
int pageIndex = i - 1;
PageNumberAndItemNumbers page = pages[pageIndex];
Assert.AreEqual(i, page.PageNumber);
Assert.AreEqual(firstItemNumber, page.FirstItemNumber);
lastItemNumber = page.LastItemNumber;
}
Assert.AreEqual(119, lastItemNumber);
Assert.IsTrue(pages[0].HasValue);
}
public void ReturnsOnePageForUnbounded()
{
IReadOnlyList <PageNumberAndItemNumbers> pagesUnbounded
= PageNumberAndItemNumbers.Calculate(0, 57);
Assert.IsNotNull(pagesUnbounded);
Assert.AreEqual(1, pagesUnbounded.Count);
Assert.AreEqual(1, pagesUnbounded[0].PageNumber);
Assert.AreEqual(1, pagesUnbounded[0].FirstItemNumber);
Assert.AreEqual(57, pagesUnbounded[0].LastItemNumber);
}
public void ReturnsOnePageForZeroItems()
{
IReadOnlyList <PageNumberAndItemNumbers> zeroPagesWithSize
= PageNumberAndItemNumbers.Calculate(20, 0);
Assert.IsNotNull(zeroPagesWithSize);
Assert.AreEqual(1, zeroPagesWithSize.Count);
Assert.AreEqual(1, zeroPagesWithSize[0].PageNumber);
Assert.AreEqual(0, zeroPagesWithSize[0].FirstItemNumber);
Assert.AreEqual(0, zeroPagesWithSize[0].LastItemNumber);
IReadOnlyList <PageNumberAndItemNumbers> zeroPagesUnbounded
= PageNumberAndItemNumbers.Calculate(0, 0);
Assert.IsNotNull(zeroPagesUnbounded);
Assert.AreEqual(1, zeroPagesUnbounded.Count);
Assert.AreEqual(1, zeroPagesUnbounded[0].PageNumber);
Assert.AreEqual(0, zeroPagesUnbounded[0].FirstItemNumber);
Assert.AreEqual(0, zeroPagesUnbounded[0].LastItemNumber);
}
public void DoesNotAllowInvalidSizes()
{
Assert.Throws <ArgumentOutOfRangeException>(
() => PageNumberAndItemNumbers.Calculate(0, -1));
}
