django/tests/pagination/tests.py

import collections.abc
import inspect
import pathlib
import unittest.mock
import warnings
from datetime import datetime

from django.core.paginator import (
    AsyncPaginator,
    BasePaginator,
    EmptyPage,
    InvalidPage,
    PageNotAnInteger,
    Paginator,
    UnorderedObjectListWarning,
)
from django.test import SimpleTestCase, TestCase

from .custom import AsyncValidAdjacentNumsPaginator, ValidAdjacentNumsPaginator
from .models import Article


class PaginationTests(SimpleTestCase):
    """
    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)

    async def check_paginator_async(self, params, output):
        """See check_paginator."""
        count, num_pages, page_range = output
        paginator = AsyncPaginator(*params)
        await self.check_attribute_async("acount", paginator, count, params)
        await self.check_attribute_async("anum_pages", paginator, num_pages, params)

    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),
        )

    async def check_attribute_async(self, name, paginator, expected, params):
        """See check_attribute."""
        got = getattr(paginator, name)
        self.assertEqual(
            expected,
            await got(),
            "For '%s', expected %s but got %s.  Paginator parameters were: %s"
            % (name, expected, got, params),
        )

    def get_test_cases_for_test_paginator(self):
        nine = [1, 2, 3, 4, 5, 6, 7, 8, 9]
        ten = nine + [10]
        eleven = ten + [11]
        return (
            # Each item is 2-tuple:
            #     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])),
        )

    def test_paginator(self):
        tests = self.get_test_cases_for_test_paginator()
        for params, output in tests:
            self.check_paginator(params, output)

    async def test_paginator_async(self):
        tests = self.get_test_cases_for_test_paginator()
        for params, output in tests:
            await self.check_paginator_async(params, output)

    def test_invalid_page_number(self):
        """
        Invalid page numbers result in the correct exception being raised.
        """
        paginator = Paginator([1, 2, 3], 2)
        with self.assertRaises(InvalidPage):
            paginator.page(3)
        with self.assertRaises(PageNotAnInteger):
            paginator.validate_number(None)
        with self.assertRaises(PageNotAnInteger):
            paginator.validate_number("x")
        with self.assertRaises(PageNotAnInteger):
            paginator.validate_number(1.2)

    async def test_invalid_apage_number_async(self):
        """See test_invalid_page_number."""
        paginator = AsyncPaginator([1, 2, 3], 2)
        with self.assertRaises(InvalidPage):
            await paginator.apage(3)

    def test_error_messages(self):
        error_messages = {
            "invalid_page": "Wrong page number",
            "min_page": "Too small",
            "no_results": "There is nothing here",
        }
        paginator = Paginator([1, 2, 3], 2, error_messages=error_messages)
        msg = "Wrong page number"
        with self.assertRaisesMessage(PageNotAnInteger, msg):
            paginator.validate_number(1.2)
        msg = "Too small"
        with self.assertRaisesMessage(EmptyPage, msg):
            paginator.validate_number(-1)
        msg = "There is nothing here"
        with self.assertRaisesMessage(EmptyPage, msg):
            paginator.validate_number(3)

        error_messages = {"min_page": "Too small"}
        paginator = Paginator([1, 2, 3], 2, error_messages=error_messages)
        # Custom message.
        msg = "Too small"
        with self.assertRaisesMessage(EmptyPage, msg):
            paginator.validate_number(-1)
        # Default message.
        msg = "That page contains no results"
        with self.assertRaisesMessage(EmptyPage, msg):
            paginator.validate_number(3)

    def test_float_integer_page(self):
        paginator = Paginator([1, 2, 3], 2)
        self.assertEqual(paginator.validate_number(1.0), 1)

    def test_no_content_allow_empty_first_page(self):
        # 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:
            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:
            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))

    async def test_paginate_misc_classes_async(self):
        class CountContainer:
            async def acount(self):
                return 42

        # AsyncPaginator can be passed other objects with an acount() method.
        paginator = AsyncPaginator(CountContainer(), 10)
        self.assertEqual(42, await paginator.acount())
        self.assertEqual(5, await paginator.anum_pages())
        self.assertEqual([1, 2, 3, 4, 5], list(await paginator.apage_range()))

        # AsyncPaginator can be passed other objects that implement __len__.
        class LenContainer:
            def __len__(self):
                return 42

        paginator = AsyncPaginator(LenContainer(), 10)
        self.assertEqual(42, await paginator.acount())
        self.assertEqual(5, await paginator.anum_pages())
        self.assertEqual([1, 2, 3, 4, 5], list(await paginator.apage_range()))

    def test_count_does_not_silence_attribute_error(self):
        class AttributeErrorContainer:
            def count(self):
                raise AttributeError("abc")

        with self.assertRaisesMessage(AttributeError, "abc"):
            Paginator(AttributeErrorContainer(), 10).count

    async def test_acount_does_not_silence_attribute_error_async(self):
        class AttributeErrorContainer:
            async def acount(self):
                raise AttributeError("abc")

        with self.assertRaisesMessage(AttributeError, "abc"):
            await AsyncPaginator(AttributeErrorContainer(), 10).acount()

    def test_count_does_not_silence_type_error(self):
        class TypeErrorContainer:
            def count(self):
                raise TypeError("abc")

        with self.assertRaisesMessage(TypeError, "abc"):
            Paginator(TypeErrorContainer(), 10).count

    async def test_acount_does_not_silence_type_error_async(self):
        class TypeErrorContainer:
            async def acount(self):
                raise TypeError("abc")

        with self.assertRaisesMessage(TypeError, "abc"):
            await AsyncPaginator(TypeErrorContainer(), 10).acount()

    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),
        )

    async def check_indexes_async(self, params, page_num, indexes):
        """See check_indexes."""
        paginator = AsyncPaginator(*params)
        if page_num == "first":
            page_num = 1
        elif page_num == "last":
            page_num = await paginator.anum_pages()
        page = await paginator.apage(page_num)
        start, end = indexes
        msg = "For %s of page %s, expected %s but got %s. Paginator parameters were: %s"
        self.assertEqual(
            start,
            await page.astart_index(),
            msg % ("start index", page_num, start, await page.astart_index(), params),
        )
        self.assertEqual(
            end,
            await page.aend_index(),
            msg % ("end index", page_num, end, await page.aend_index(), params),
        )

    def get_test_cases_for_test_page_indexes(self):
        ten = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
        return (
            # Each item is 3-tuple:
            #     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)),
        )

    def test_page_indexes(self):
        """
        Paginator pages have the correct start and end indexes.
        """
        tests = self.get_test_cases_for_test_page_indexes()
        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.
        with self.assertRaises(EmptyPage):
            self.check_indexes(([], 4, 0, False), 1, None)
        with self.assertRaises(EmptyPage):
            self.check_indexes(([], 4, 1, False), 1, None)
        with self.assertRaises(EmptyPage):
            self.check_indexes(([], 4, 2, False), 1, None)

    async def test_page_indexes_async(self):
        """See test_page_indexes"""
        tests = self.get_test_cases_for_test_page_indexes()
        for params, first, last in tests:
            await self.check_indexes_async(params, "first", first)
            await self.check_indexes_async(params, "last", last)

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

    def test_page_sequence(self):
        """
        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.assertIn("k", page2)
        self.assertNotIn("a", page2)
        self.assertEqual("".join(page2), "fghijk")
        self.assertEqual("".join(reversed(page2)), "kjihgf")

    async def test_page_sequence_async(self):
        eleven = "abcdefghijk"
        page2 = await AsyncPaginator(eleven, per_page=5, orphans=1).apage(2)
        await page2.aget_object_list()
        self.assertEqual(len(page2), 6)
        self.assertIn("k", page2)
        self.assertNotIn("a", page2)
        self.assertEqual("".join(page2), "fghijk")
        self.assertEqual("".join(reversed(page2)), "kjihgf")

    def test_get_page_hook(self):
        """
        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())

    async def test_get_page_hook_async(self):
        """
        An AsyncPaginator subclass can use the ``_get_page`` hook to
        return an alternative to the standard AsyncPage class.
        """
        eleven = "abcdefghijk"
        paginator = AsyncValidAdjacentNumsPaginator(eleven, per_page=6)
        page1 = await paginator.apage(1)
        page2 = await paginator.apage(2)
        self.assertIsNone(await page1.aprevious_page_number())
        self.assertEqual(await page1.anext_page_number(), 2)
        self.assertEqual(await page2.aprevious_page_number(), 1)
        self.assertIsNone(await page2.anext_page_number())

    def test_page_range_iterator(self):
        """
        Paginator.page_range should be an iterator.
        """
        self.assertIsInstance(Paginator([1, 2, 3], 2).page_range, type(range(0)))

    def test_get_page(self):
        """
        Paginator.get_page() returns a valid page even with invalid page
        arguments.
        """
        paginator = Paginator([1, 2, 3], 2)
        page = paginator.get_page(1)
        self.assertEqual(page.number, 1)
        self.assertEqual(page.object_list, [1, 2])
        # An empty page returns the last page.
        self.assertEqual(paginator.get_page(3).number, 2)
        # Non-integer page returns the first page.
        self.assertEqual(paginator.get_page(None).number, 1)

    async def test_aget_page_async(self):
        """
        AsyncPaginator.aget_page() returns a valid page even with invalid page
        arguments.
        """
        paginator = AsyncPaginator([1, 2, 3], 2)
        page = await paginator.aget_page(1)
        self.assertEqual(page.number, 1)
        self.assertEqual(page.object_list, [1, 2])
        # An empty page returns the last page.
        self.assertEqual((await paginator.aget_page(3)).number, 2)
        # Non-integer page returns the first page.
        self.assertEqual((await paginator.aget_page(None)).number, 1)

    def test_get_page_empty_object_list(self):
        """Paginator.get_page() with an empty object_list."""
        paginator = Paginator([], 2)
        # An empty page returns the last page.
        self.assertEqual(paginator.get_page(1).number, 1)
        self.assertEqual(paginator.get_page(2).number, 1)
        # Non-integer page returns the first page.
        self.assertEqual(paginator.get_page(None).number, 1)

    async def test_aget_page_empty_object_list_async(self):
        """AsyncPaginator.aget_page() with an empty object_list."""
        paginator = AsyncPaginator([], 2)
        # An empty page returns the last page.
        self.assertEqual((await paginator.aget_page(1)).number, 1)
        self.assertEqual((await paginator.aget_page(2)).number, 1)
        # Non-integer page returns the first page.
        self.assertEqual((await paginator.aget_page(None)).number, 1)

    def test_get_page_empty_object_list_and_allow_empty_first_page_false(self):
        """
        Paginator.get_page() raises EmptyPage if allow_empty_first_page=False
        and object_list is empty.
        """
        paginator = Paginator([], 2, allow_empty_first_page=False)
        with self.assertRaises(EmptyPage):
            paginator.get_page(1)

    async def test_aget_page_empty_obj_list_and_allow_empty_first_page_false_async(
        self,
    ):
        """
        AsyncPaginator.aget_page() raises EmptyPage if allow_empty_first_page=False
        and object_list is empty.
        """
        paginator = AsyncPaginator([], 2, allow_empty_first_page=False)
        with self.assertRaises(EmptyPage):
            await paginator.aget_page(1)

    def test_paginator_iteration(self):
        paginator = Paginator([1, 2, 3], 2)
        page_iterator = iter(paginator)
        for page, expected in enumerate(([1, 2], [3]), start=1):
            with self.subTest(page=page):
                self.assertEqual(expected, list(next(page_iterator)))

        self.assertEqual(
            [str(page) for page in iter(paginator)],
            ["<Page 1 of 2>", "<Page 2 of 2>"],
        )

    async def test_paginator_iteration_async(self):
        paginator = AsyncPaginator([1, 2, 3], 2)
        page_iterator = aiter(paginator)
        for page, expected in enumerate(([1, 2], [3]), start=1):
            with self.subTest(page=page):
                async_page = await anext(page_iterator)
                self.assertEqual(expected, [obj async for obj in async_page])
        self.assertEqual(
            [str(page) async for page in aiter(paginator)],
            ["<Async Page 1>", "<Async Page 2>"],
        )

    def get_test_cases_for_test_get_elided_page_range(self):
        ELLIPSIS = Paginator.ELLIPSIS
        return [
            # on_each_side=2, on_ends=1
            (1, 2, 1, [1, 2, 3, ELLIPSIS, 50]),
            (4, 2, 1, [1, 2, 3, 4, 5, 6, ELLIPSIS, 50]),
            (5, 2, 1, [1, 2, 3, 4, 5, 6, 7, ELLIPSIS, 50]),
            (6, 2, 1, [1, ELLIPSIS, 4, 5, 6, 7, 8, ELLIPSIS, 50]),
            (45, 2, 1, [1, ELLIPSIS, 43, 44, 45, 46, 47, ELLIPSIS, 50]),
            (46, 2, 1, [1, ELLIPSIS, 44, 45, 46, 47, 48, 49, 50]),
            (47, 2, 1, [1, ELLIPSIS, 45, 46, 47, 48, 49, 50]),
            (50, 2, 1, [1, ELLIPSIS, 48, 49, 50]),
            # on_each_side=1, on_ends=3
            (1, 1, 3, [1, 2, ELLIPSIS, 48, 49, 50]),
            (5, 1, 3, [1, 2, 3, 4, 5, 6, ELLIPSIS, 48, 49, 50]),
            (6, 1, 3, [1, 2, 3, 4, 5, 6, 7, ELLIPSIS, 48, 49, 50]),
            (7, 1, 3, [1, 2, 3, ELLIPSIS, 6, 7, 8, ELLIPSIS, 48, 49, 50]),
            (44, 1, 3, [1, 2, 3, ELLIPSIS, 43, 44, 45, ELLIPSIS, 48, 49, 50]),
            (45, 1, 3, [1, 2, 3, ELLIPSIS, 44, 45, 46, 47, 48, 49, 50]),
            (46, 1, 3, [1, 2, 3, ELLIPSIS, 45, 46, 47, 48, 49, 50]),
            (50, 1, 3, [1, 2, 3, ELLIPSIS, 49, 50]),
            # on_each_side=4, on_ends=0
            (1, 4, 0, [1, 2, 3, 4, 5, ELLIPSIS]),
            (5, 4, 0, [1, 2, 3, 4, 5, 6, 7, 8, 9, ELLIPSIS]),
            (6, 4, 0, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ELLIPSIS]),
            (7, 4, 0, [ELLIPSIS, 3, 4, 5, 6, 7, 8, 9, 10, 11, ELLIPSIS]),
            (44, 4, 0, [ELLIPSIS, 40, 41, 42, 43, 44, 45, 46, 47, 48, ELLIPSIS]),
            (45, 4, 0, [ELLIPSIS, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
            (46, 4, 0, [ELLIPSIS, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
            (50, 4, 0, [ELLIPSIS, 46, 47, 48, 49, 50]),
            # on_each_side=0, on_ends=1
            (1, 0, 1, [1, ELLIPSIS, 50]),
            (2, 0, 1, [1, 2, ELLIPSIS, 50]),
            (3, 0, 1, [1, 2, 3, ELLIPSIS, 50]),
            (4, 0, 1, [1, ELLIPSIS, 4, ELLIPSIS, 50]),
            (47, 0, 1, [1, ELLIPSIS, 47, ELLIPSIS, 50]),
            (48, 0, 1, [1, ELLIPSIS, 48, 49, 50]),
            (49, 0, 1, [1, ELLIPSIS, 49, 50]),
            (50, 0, 1, [1, ELLIPSIS, 50]),
            # on_each_side=0, on_ends=0
            (1, 0, 0, [1, ELLIPSIS]),
            (2, 0, 0, [1, 2, ELLIPSIS]),
            (3, 0, 0, [ELLIPSIS, 3, ELLIPSIS]),
            (48, 0, 0, [ELLIPSIS, 48, ELLIPSIS]),
            (49, 0, 0, [ELLIPSIS, 49, 50]),
            (50, 0, 0, [ELLIPSIS, 50]),
        ]

    def test_get_elided_page_range(self):
        # Paginator.validate_number() must be called:
        paginator = Paginator([1, 2, 3], 2)
        with unittest.mock.patch.object(paginator, "validate_number") as mock:
            mock.assert_not_called()
            list(paginator.get_elided_page_range(2))
            mock.assert_called_with(2)

        ELLIPSIS = Paginator.ELLIPSIS

        # Range is not elided if not enough pages when using default arguments:
        paginator = Paginator(range(10 * 100), 100)
        page_range = paginator.get_elided_page_range(1)
        self.assertIsInstance(page_range, collections.abc.Generator)
        self.assertNotIn(ELLIPSIS, page_range)
        paginator = Paginator(range(10 * 100 + 1), 100)
        self.assertIsInstance(page_range, collections.abc.Generator)
        page_range = paginator.get_elided_page_range(1)
        self.assertIn(ELLIPSIS, page_range)

        # Range should be elided if enough pages when using default arguments:
        tests = [
            # on_each_side=3, on_ends=2
            (1, [1, 2, 3, 4, ELLIPSIS, 49, 50]),
            (6, [1, 2, 3, 4, 5, 6, 7, 8, 9, ELLIPSIS, 49, 50]),
            (7, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ELLIPSIS, 49, 50]),
            (8, [1, 2, ELLIPSIS, 5, 6, 7, 8, 9, 10, 11, ELLIPSIS, 49, 50]),
            (43, [1, 2, ELLIPSIS, 40, 41, 42, 43, 44, 45, 46, ELLIPSIS, 49, 50]),
            (44, [1, 2, ELLIPSIS, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
            (45, [1, 2, ELLIPSIS, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
            (50, [1, 2, ELLIPSIS, 47, 48, 49, 50]),
        ]
        paginator = Paginator(range(5000), 100)
        for number, expected in tests:
            with self.subTest(number=number):
                page_range = paginator.get_elided_page_range(number)
                self.assertIsInstance(page_range, collections.abc.Generator)
                self.assertEqual(list(page_range), expected)

        # Range is not elided if not enough pages when using custom arguments:
        tests = [
            (6, 2, 1, 1),
            (8, 1, 3, 1),
            (8, 4, 0, 1),
            (4, 1, 1, 1),
            # When on_each_side and on_ends are both <= 1 but not both == 1 it
            # is a special case where the range is not elided until an extra
            # page is added.
            (2, 0, 1, 2),
            (2, 1, 0, 2),
            (1, 0, 0, 2),
        ]
        for pages, on_each_side, on_ends, elided_after in tests:
            for offset in range(elided_after + 1):
                with self.subTest(
                    pages=pages,
                    offset=elided_after,
                    on_each_side=on_each_side,
                    on_ends=on_ends,
                ):
                    paginator = Paginator(range((pages + offset) * 100), 100)
                    page_range = paginator.get_elided_page_range(
                        1,
                        on_each_side=on_each_side,
                        on_ends=on_ends,
                    )
                    self.assertIsInstance(page_range, collections.abc.Generator)
                    if offset < elided_after:
                        self.assertNotIn(ELLIPSIS, page_range)
                    else:
                        self.assertIn(ELLIPSIS, page_range)

        # Range should be elided if enough pages when using custom arguments:
        tests = self.get_test_cases_for_test_get_elided_page_range()
        paginator = Paginator(range(5000), 100)
        for number, on_each_side, on_ends, expected in tests:
            with self.subTest(
                number=number, on_each_side=on_each_side, on_ends=on_ends
            ):
                page_range = paginator.get_elided_page_range(
                    number,
                    on_each_side=on_each_side,
                    on_ends=on_ends,
                )
                self.assertIsInstance(page_range, collections.abc.Generator)
                self.assertEqual(list(page_range), expected)

    async def test_aget_elided_page_range_async(self):
        # AsyncPaginator.avalidate_number() must be called:
        paginator = AsyncPaginator([1, 2, 3], 2)
        with unittest.mock.patch.object(paginator, "avalidate_number") as mock:
            mock.assert_not_called()
            [p async for p in paginator.aget_elided_page_range(2)]
            mock.assert_called_with(2)

        ELLIPSIS = Paginator.ELLIPSIS

        # Range is not elided if not enough pages when using default arguments:
        paginator = AsyncPaginator(range(10 * 100), 100)
        page_range = paginator.aget_elided_page_range(1)
        self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
        self.assertNotIn(ELLIPSIS, [p async for p in page_range])
        paginator = AsyncPaginator(range(10 * 100 + 1), 100)
        self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
        page_range = paginator.aget_elided_page_range(1)
        self.assertIn(ELLIPSIS, [p async for p in page_range])

        # Range should be elided if enough pages when using default arguments:
        tests = [
            # on_each_side=3, on_ends=2
            (1, [1, 2, 3, 4, ELLIPSIS, 49, 50]),
            (6, [1, 2, 3, 4, 5, 6, 7, 8, 9, ELLIPSIS, 49, 50]),
            (7, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ELLIPSIS, 49, 50]),
            (8, [1, 2, ELLIPSIS, 5, 6, 7, 8, 9, 10, 11, ELLIPSIS, 49, 50]),
            (43, [1, 2, ELLIPSIS, 40, 41, 42, 43, 44, 45, 46, ELLIPSIS, 49, 50]),
            (44, [1, 2, ELLIPSIS, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
            (45, [1, 2, ELLIPSIS, 42, 43, 44, 45, 46, 47, 48, 49, 50]),
            (50, [1, 2, ELLIPSIS, 47, 48, 49, 50]),
        ]
        paginator = AsyncPaginator(range(5000), 100)
        for number, expected in tests:
            with self.subTest(number=number):
                page_range = paginator.aget_elided_page_range(number)
                self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
                self.assertEqual([p async for p in page_range], expected)

        # Range is not elided if not enough pages when using custom arguments:
        tests = [
            (6, 2, 1, 1),
            (8, 1, 3, 1),
            (8, 4, 0, 1),
            (4, 1, 1, 1),
            # When on_each_side and on_ends are both <= 1 but not both == 1 it
            # is a special case where the range is not elided until an extra
            # page is added.
            (2, 0, 1, 2),
            (2, 1, 0, 2),
            (1, 0, 0, 2),
        ]
        for pages, on_each_side, on_ends, elided_after in tests:
            for offset in range(elided_after + 1):
                with self.subTest(
                    pages=pages,
                    offset=elided_after,
                    on_each_side=on_each_side,
                    on_ends=on_ends,
                ):
                    paginator = AsyncPaginator(range((pages + offset) * 100), 100)
                    page_range = paginator.aget_elided_page_range(
                        1,
                        on_each_side=on_each_side,
                        on_ends=on_ends,
                    )
                    self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
                    page_list = [p async for p in page_range]
                    if offset < elided_after:
                        self.assertNotIn(ELLIPSIS, page_list)
                    else:
                        self.assertIn(ELLIPSIS, page_list)

        # Range should be elided if enough pages when using custom arguments:
        tests = self.get_test_cases_for_test_get_elided_page_range()
        paginator = AsyncPaginator(range(5000), 100)
        for number, on_each_side, on_ends, expected in tests:
            with self.subTest(
                number=number, on_each_side=on_each_side, on_ends=on_ends
            ):
                page_range = paginator.aget_elided_page_range(
                    number,
                    on_each_side=on_each_side,
                    on_ends=on_ends,
                )
                self.assertIsInstance(page_range, collections.abc.AsyncGenerator)
                self.assertEqual([p async for p in page_range], expected)


class ModelPaginationTests(TestCase):
    """
    Test pagination with Django model instances
    """

    @classmethod
    def setUpTestData(cls):
        # Prepare a list of objects for pagination.
        pub_date = datetime(2005, 7, 29)
        cls.articles = [
            Article.objects.create(headline=f"Article {x}", pub_date=pub_date)
            for x in range(1, 10)
        ]

    def test_first_page(self):
        paginator = Paginator(Article.objects.order_by("id"), 5)
        p = paginator.page(1)
        self.assertEqual("<Page 1 of 2>", str(p))
        self.assertSequenceEqual(p.object_list, self.articles[:5])
        self.assertTrue(p.has_next())
        self.assertFalse(p.has_previous())
        self.assertTrue(p.has_other_pages())
        self.assertEqual(2, p.next_page_number())
        with self.assertRaises(InvalidPage):
            p.previous_page_number()
        self.assertEqual(1, p.start_index())
        self.assertEqual(5, p.end_index())

    async def test_first_page_async(self):
        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
        p = await paginator.apage(1)
        self.assertEqual("<Async Page 1>", str(p))
        object_list = await p.aget_object_list()
        self.assertSequenceEqual(object_list, self.articles[:5])
        self.assertTrue(await p.ahas_next())
        self.assertFalse(await p.ahas_previous())
        self.assertTrue(await p.ahas_other_pages())
        self.assertEqual(2, await p.anext_page_number())
        with self.assertRaises(InvalidPage):
            await p.aprevious_page_number()
        self.assertEqual(1, await p.astart_index())
        self.assertEqual(5, await p.aend_index())

    def test_last_page(self):
        paginator = Paginator(Article.objects.order_by("id"), 5)
        p = paginator.page(2)
        self.assertEqual("<Page 2 of 2>", str(p))
        self.assertSequenceEqual(p.object_list, self.articles[5:])
        self.assertFalse(p.has_next())
        self.assertTrue(p.has_previous())
        self.assertTrue(p.has_other_pages())
        with 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())

    async def test_last_page_async(self):
        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
        p = await paginator.apage(2)
        self.assertEqual("<Async Page 2>", str(p))
        object_list = await p.aget_object_list()
        self.assertSequenceEqual(object_list, self.articles[5:])
        self.assertFalse(await p.ahas_next())
        self.assertTrue(await p.ahas_previous())
        self.assertTrue(await p.ahas_other_pages())
        with self.assertRaises(InvalidPage):
            await p.anext_page_number()
        self.assertEqual(1, await p.aprevious_page_number())
        self.assertEqual(6, await p.astart_index())
        self.assertEqual(9, await p.aend_index())

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

        # object_list queryset is not evaluated by an invalid __getitem__ call.
        # (this happens from the template engine when using e.g.:
        # {% page_obj.has_previous %}).
        self.assertIsNone(p.object_list._result_cache)
        msg = "Page indices must be integers or slices, not str."
        with self.assertRaisesMessage(TypeError, msg):
            p["has_previous"]
        self.assertIsNone(p.object_list._result_cache)
        self.assertNotIsInstance(p.object_list, list)

        # Make sure slicing the Page object with numbers and slice objects work.
        self.assertEqual(p[0], self.articles[0])
        self.assertSequenceEqual(p[slice(2)], self.articles[:2])
        # After __getitem__ is called, object_list is a list
        self.assertIsInstance(p.object_list, list)

    async def test_page_getitem_async(self):
        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
        p = await paginator.apage(1)

        msg = "AsyncPage indices must be integers or slices, not str."
        with self.assertRaisesMessage(TypeError, msg):
            p["has_previous"]

        self.assertIsNone(p.object_list._result_cache)

        self.assertNotIsInstance(p.object_list, list)

        await p.aget_object_list()

        self.assertEqual(p[0], self.articles[0])
        self.assertSequenceEqual(p[slice(2)], self.articles[:2])
        self.assertIsInstance(p.object_list, list)

    def test_paginating_unordered_queryset_raises_warning(self):
        msg = (
            "Pagination may yield inconsistent results with an unordered "
            "object_list: <class 'pagination.models.Article'> QuerySet."
        )
        with self.assertWarnsMessage(UnorderedObjectListWarning, msg) as cm:
            Paginator(Article.objects.all(), 5)
        # The warning points at the Paginator caller (i.e. the stacklevel
        # is appropriate).
        self.assertEqual(cm.filename, __file__)

    async def test_paginating_unordered_queryset_raises_warning_async(self):
        msg = (
            "Pagination may yield inconsistent results with an unordered "
            "object_list: <class 'pagination.models.Article'> QuerySet."
        )
        with self.assertWarnsMessage(UnorderedObjectListWarning, msg) as cm:
            AsyncPaginator(Article.objects.all(), 5)
        # The warning points at the BasePaginator caller.
        # The reason is that the UnorderedObjectListWarning occurs in BasePaginator.
        base_paginator_path = pathlib.Path(inspect.getfile(BasePaginator))
        self.assertIn(
            cm.filename,
            [str(base_paginator_path), str(base_paginator_path.with_suffix(".py"))],
        )

    def test_paginating_empty_queryset_does_not_warn(self):
        with warnings.catch_warnings(record=True) as recorded:
            Paginator(Article.objects.none(), 5)
        self.assertEqual(len(recorded), 0)

    async def test_paginating_empty_queryset_does_not_warn_async(self):
        with warnings.catch_warnings(record=True) as recorded:
            AsyncPaginator(Article.objects.none(), 5)
        self.assertEqual(len(recorded), 0)

    def test_paginating_unordered_object_list_raises_warning(self):
        """
        Unordered object list warning with an object that has an ordered
        attribute but not a model attribute.
        """

        class ObjectList:
            ordered = False

        object_list = ObjectList()
        msg = (
            "Pagination may yield inconsistent results with an unordered "
            "object_list: {!r}.".format(object_list)
        )
        with self.assertWarnsMessage(UnorderedObjectListWarning, msg):
            Paginator(object_list, 5)

    async def test_paginating_unordered_object_list_raises_warning_async(self):
        """
        See test_paginating_unordered_object_list_raises_warning.
        """

        class ObjectList:
            ordered = False

        object_list = ObjectList()
        msg = (
            "Pagination may yield inconsistent results with an unordered "
            "object_list: {!r}.".format(object_list)
        )
        with self.assertWarnsMessage(UnorderedObjectListWarning, msg):
            AsyncPaginator(object_list, 5)

    async def test_async_page_object_list_raises_type_error_before_await(self):
        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
        p = await paginator.apage(1)

        with self.subTest(func="len"):
            msg = "AsyncPage.aget_object_list() must be awaited before calling len()."
            with self.assertRaisesMessage(TypeError, msg):
                len(p)

        with self.subTest(func="reversed"):
            msg = (
                "AsyncPage.aget_object_list() must be awaited before calling "
                "reversed()."
            )
            with self.assertRaisesMessage(TypeError, msg):
                reversed(p)

        with self.subTest(func="index"):
            msg = "AsyncPage.aget_object_list() must be awaited before using indexing."
            with self.assertRaisesMessage(TypeError, msg):
                p[0]

    async def test_async_page_aiteration(self):
        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
        p = await paginator.apage(1)
        object_list = [obj async for obj in p]
        self.assertEqual(len(object_list), 5)

    async def test_aget_object_list(self):
        paginator = AsyncPaginator(Article.objects.order_by("id"), 5)
        p = await paginator.apage(1)

        # object_list queryset is converted to list.
        first_called_objs = await p.aget_object_list()
        self.assertIsInstance(first_called_objs, list)
        # It returns the same list that was converted on the first call.
        second_called_objs = await p.aget_object_list()
        self.assertEqual(id(first_called_objs), id(second_called_objs))