django/tests/pagination/tests.py

from __future__ import absolute_import, unicode_literals

from datetime import datetime

from django.core.paginator import (Paginator, EmptyPage, InvalidPage,
    PageNotAnInteger)
from django.test import TestCase
from django.utils import six
from django.utils import unittest

from .models import Article
from .custom import ValidAdjacentNumsPaginator


class PaginationTests(unittest.TestCase):
    """
    Tests for the Paginator and Page classes.
    """

    def check_paginator(self, params, output):
        """
        Helper method that instantiates a Paginator object from the passed
        params and then checks that its attributes match the passed output.
        """
        count, num_pages, page_range = output
        paginator = Paginator(*params)
        self.check_attribute('count', paginator, count, params)
        self.check_attribute('num_pages', paginator, num_pages, params)
        self.check_attribute('page_range', paginator, page_range, params, coerce=list)

    def check_attribute(self, name, paginator, expected, params, coerce=None):
        """
        Helper method that checks a single attribute and gives a nice error
        message upon test failure.
        """
        got = getattr(paginator, name)
        if coerce is not None:
            got = coerce(got)
        self.assertEqual(expected, got,
            "For '%s', expected %s but got %s.  Paginator parameters were: %s"
            % (name, expected, got, params))

    def test_paginator(self):
        """
        Tests the paginator attributes using varying inputs.
        """
        nine = [1, 2, 3, 4, 5, 6, 7, 8, 9]
        ten = nine + [10]
        eleven = ten + [11]
        tests = (
            # Each item is two tuples:
            #     First tuple is Paginator parameters - object_list, per_page,
            #         orphans, and allow_empty_first_page.
            #     Second tuple is resulting Paginator attributes - count,
            #         num_pages, and page_range.
            # Ten items, varying orphans, no empty first page.
            ((ten, 4, 0, False), (10, 3, [1, 2, 3])),
            ((ten, 4, 1, False), (10, 3, [1, 2, 3])),
            ((ten, 4, 2, False), (10, 2, [1, 2])),
            ((ten, 4, 5, False), (10, 2, [1, 2])),
            ((ten, 4, 6, False), (10, 1, [1])),
            # Ten items, varying orphans, allow empty first page.
            ((ten, 4, 0, True), (10, 3, [1, 2, 3])),
            ((ten, 4, 1, True), (10, 3, [1, 2, 3])),
            ((ten, 4, 2, True), (10, 2, [1, 2])),
            ((ten, 4, 5, True), (10, 2, [1, 2])),
            ((ten, 4, 6, True), (10, 1, [1])),
            # One item, varying orphans, no empty first page.
            (([1], 4, 0, False), (1, 1, [1])),
            (([1], 4, 1, False), (1, 1, [1])),
            (([1], 4, 2, False), (1, 1, [1])),
            # One item, varying orphans, allow empty first page.
            (([1], 4, 0, True), (1, 1, [1])),
            (([1], 4, 1, True), (1, 1, [1])),
            (([1], 4, 2, True), (1, 1, [1])),
            # Zero items, varying orphans, no empty first page.
            (([], 4, 0, False), (0, 0, [])),
            (([], 4, 1, False), (0, 0, [])),
            (([], 4, 2, False), (0, 0, [])),
            # Zero items, varying orphans, allow empty first page.
            (([], 4, 0, True), (0, 1, [1])),
            (([], 4, 1, True), (0, 1, [1])),
            (([], 4, 2, True), (0, 1, [1])),
            # Number if items one less than per_page.
            (([], 1, 0, True), (0, 1, [1])),
            (([], 1, 0, False), (0, 0, [])),
            (([1], 2, 0, True), (1, 1, [1])),
            ((nine, 10, 0, True), (9, 1, [1])),
            # Number if items equal to per_page.
            (([1], 1, 0, True), (1, 1, [1])),
            (([1, 2], 2, 0, True), (2, 1, [1])),
            ((ten, 10, 0, True), (10, 1, [1])),
            # Number if items one more than per_page.
            (([1, 2], 1, 0, True), (2, 2, [1, 2])),
            (([1, 2, 3], 2, 0, True), (3, 2, [1, 2])),
            ((eleven, 10, 0, True), (11, 2, [1, 2])),
            # Number if items one more than per_page with one orphan.
            (([1, 2], 1, 1, True), (2, 1, [1])),
            (([1, 2, 3], 2, 1, True), (3, 1, [1])),
            ((eleven, 10, 1, True), (11, 1, [1])),
            # Non-integer inputs
            ((ten, '4', 1, False), (10, 3, [1, 2, 3])),
            ((ten, '4', 1, False), (10, 3, [1, 2, 3])),
            ((ten, 4, '1', False), (10, 3, [1, 2, 3])),
            ((ten, 4, '1', False), (10, 3, [1, 2, 3])),
        )
        for params, output in tests:
            self.check_paginator(params, output)

    def test_invalid_page_number(self):
        """
        Tests that invalid page numbers result in the correct exception being
        raised.
        """
        paginator = Paginator([1, 2, 3], 2)
        self.assertRaises(InvalidPage, paginator.page, 3)
        self.assertRaises(PageNotAnInteger, paginator.validate_number, None)
        self.assertRaises(PageNotAnInteger, paginator.validate_number, 'x')
        # With no content and allow_empty_first_page=True, 1 is a valid page number
        paginator = Paginator([], 2)
        self.assertEqual(paginator.validate_number(1), 1)

    def test_paginate_misc_classes(self):
        class CountContainer(object):
            def count(self):
                return 42
        # Paginator can be passed other objects with a count() method.
        paginator = Paginator(CountContainer(), 10)
        self.assertEqual(42, paginator.count)
        self.assertEqual(5, paginator.num_pages)
        self.assertEqual([1, 2, 3, 4, 5], list(paginator.page_range))

        # Paginator can be passed other objects that implement __len__.
        class LenContainer(object):
            def __len__(self):
                return 42
        paginator = Paginator(LenContainer(), 10)
        self.assertEqual(42, paginator.count)
        self.assertEqual(5, paginator.num_pages)
        self.assertEqual([1, 2, 3, 4, 5], list(paginator.page_range))

    def check_indexes(self, params, page_num, indexes):
        """
        Helper method that instantiates a Paginator object from the passed
        params and then checks that the start and end indexes of the passed
        page_num match those given as a 2-tuple in indexes.
        """
        paginator = Paginator(*params)
        if page_num == 'first':
            page_num = 1
        elif page_num == 'last':
            page_num = paginator.num_pages
        page = paginator.page(page_num)
        start, end = indexes
        msg = ("For %s of page %s, expected %s but got %s."
               " Paginator parameters were: %s")
        self.assertEqual(start, page.start_index(),
            msg % ('start index', page_num, start, page.start_index(), params))
        self.assertEqual(end, page.end_index(),
            msg % ('end index', page_num, end, page.end_index(), params))

    def test_page_indexes(self):
        """
        Tests that paginator pages have the correct start and end indexes.
        """
        ten = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
        tests = (
            # Each item is three tuples:
            #     First tuple is Paginator parameters - object_list, per_page,
            #         orphans, and allow_empty_first_page.
            #     Second tuple is the start and end indexes of the first page.
            #     Third tuple is the start and end indexes of the last page.
            # Ten items, varying per_page, no orphans.
            ((ten, 1, 0, True), (1, 1), (10, 10)),
            ((ten, 2, 0, True), (1, 2), (9, 10)),
            ((ten, 3, 0, True), (1, 3), (10, 10)),
            ((ten, 5, 0, True), (1, 5), (6, 10)),
            # Ten items, varying per_page, with orphans.
            ((ten, 1, 1, True), (1, 1), (9, 10)),
            ((ten, 1, 2, True), (1, 1), (8, 10)),
            ((ten, 3, 1, True), (1, 3), (7, 10)),
            ((ten, 3, 2, True), (1, 3), (7, 10)),
            ((ten, 3, 4, True), (1, 3), (4, 10)),
            ((ten, 5, 1, True), (1, 5), (6, 10)),
            ((ten, 5, 2, True), (1, 5), (6, 10)),
            ((ten, 5, 5, True), (1, 10), (1, 10)),
            # One item, varying orphans, no empty first page.
            (([1], 4, 0, False), (1, 1), (1, 1)),
            (([1], 4, 1, False), (1, 1), (1, 1)),
            (([1], 4, 2, False), (1, 1), (1, 1)),
            # One item, varying orphans, allow empty first page.
            (([1], 4, 0, True), (1, 1), (1, 1)),
            (([1], 4, 1, True), (1, 1), (1, 1)),
            (([1], 4, 2, True), (1, 1), (1, 1)),
            # Zero items, varying orphans, allow empty first page.
            (([], 4, 0, True), (0, 0), (0, 0)),
            (([], 4, 1, True), (0, 0), (0, 0)),
            (([], 4, 2, True), (0, 0), (0, 0)),
        )
        for params, first, last in tests:
            self.check_indexes(params, 'first', first)
            self.check_indexes(params, 'last', last)

        # When no items and no empty first page, we should get EmptyPage error.
        self.assertRaises(EmptyPage, self.check_indexes, ([], 4, 0, False), 1, None)
        self.assertRaises(EmptyPage, self.check_indexes, ([], 4, 1, False), 1, None)
        self.assertRaises(EmptyPage, self.check_indexes, ([], 4, 2, False), 1, None)

    def test_page_sequence(self):
        """
        Tests that a paginator page acts like a standard sequence.
        """
        eleven = 'abcdefghijk'
        page2 = Paginator(eleven, per_page=5, orphans=1).page(2)
        self.assertEqual(len(page2), 6)
        self.assertTrue('k' in page2)
        self.assertFalse('a' in page2)
        self.assertEqual(''.join(page2), 'fghijk')
        self.assertEqual(''.join(reversed(page2)), 'kjihgf')

    def test_get_page_hook(self):
        """
        Tests that a Paginator subclass can use the ``_get_page`` hook to
        return an alternative to the standard Page class.
        """
        eleven = 'abcdefghijk'
        paginator = ValidAdjacentNumsPaginator(eleven, per_page=6)
        page1 = paginator.page(1)
        page2 = paginator.page(2)
        self.assertIsNone(page1.previous_page_number())
        self.assertEqual(page1.next_page_number(), 2)
        self.assertEqual(page2.previous_page_number(), 1)
        self.assertIsNone(page2.next_page_number())


class ModelPaginationTests(TestCase):
    """
    Test pagination with Django model instances
    """
    def setUp(self):
        # Prepare a list of objects for pagination.
        for x in range(1, 10):
            a = Article(headline='Article %s' % x, pub_date=datetime(2005, 7, 29))
            a.save()

    def test_first_page(self):
        paginator = Paginator(Article.objects.all(), 5)
        p = paginator.page(1)
        self.assertEqual("<Page 1 of 2>", six.text_type(p))
        self.assertQuerysetEqual(p.object_list, [
                "<Article: Article 1>",
                "<Article: Article 2>",
                "<Article: Article 3>",
                "<Article: Article 4>",
                "<Article: Article 5>"
            ],
            ordered=False
        )
        self.assertTrue(p.has_next())
        self.assertFalse(p.has_previous())
        self.assertTrue(p.has_other_pages())
        self.assertEqual(2, p.next_page_number())
        self.assertRaises(InvalidPage, p.previous_page_number)
        self.assertEqual(1, p.start_index())
        self.assertEqual(5, p.end_index())

    def test_last_page(self):
        paginator = Paginator(Article.objects.all(), 5)
        p = paginator.page(2)
        self.assertEqual("<Page 2 of 2>", six.text_type(p))
        self.assertQuerysetEqual(p.object_list, [
                "<Article: Article 6>",
                "<Article: Article 7>",
                "<Article: Article 8>",
                "<Article: Article 9>"
            ],
            ordered=False
        )
        self.assertFalse(p.has_next())
        self.assertTrue(p.has_previous())
        self.assertTrue(p.has_other_pages())
        self.assertRaises(InvalidPage, p.next_page_number)
        self.assertEqual(1, p.previous_page_number())
        self.assertEqual(6, p.start_index())
        self.assertEqual(9, p.end_index())

    def test_page_getitem(self):
        """
        Tests proper behaviour of a paginator page __getitem__ (queryset
        evaluation, slicing, exception raised).
        """
        paginator = Paginator(Article.objects.all(), 5)
        p = paginator.page(1)

        # Make sure object_list queryset is not evaluated by an invalid __getitem__ call.
        # (this happens from the template engine when using eg: {% page_obj.has_previous %})
        self.assertIsNone(p.object_list._result_cache)
        self.assertRaises(TypeError, lambda: p['has_previous'])
        self.assertIsNone(p.object_list._result_cache)

        # Make sure slicing the Page object with numbers and slice objects work.
        self.assertEqual(p[0], Article.objects.get(headline='Article 1'))
        self.assertQuerysetEqual(p[slice(2)], [
                "<Article: Article 1>",
                "<Article: Article 2>",
            ]
        )