# coding: utf-8 from __future__ import unicode_literals import pytest from django.core.paginator import Paginator as DjangoPaginator from django.db import models from django.test import TestCase from rest_framework import ( exceptions, filters, generics, pagination, serializers, status ) from rest_framework.pagination import PAGE_BREAK, PageLink from rest_framework.request import Request from rest_framework.test import APIRequestFactory factory = APIRequestFactory() class TestPaginationIntegration: """ Integration tests. """ def setup(self): class PassThroughSerializer(serializers.BaseSerializer): def to_representation(self, item): return item class EvenItemsOnly(filters.BaseFilterBackend): def filter_queryset(self, request, queryset, view): return [item for item in queryset if item % 2 == 0] class BasicPagination(pagination.PageNumberPagination): page_size = 5 page_size_query_param = 'page_size' max_page_size = 20 self.view = generics.ListAPIView.as_view( serializer_class=PassThroughSerializer, queryset=range(1, 101), filter_backends=[EvenItemsOnly], pagination_class=BasicPagination ) def test_filtered_items_are_paginated(self): request = factory.get('/', {'page': 2}) response = self.view(request) assert response.status_code == status.HTTP_200_OK assert response.data == { 'results': [12, 14, 16, 18, 20], 'previous': 'http://testserver/', 'next': 'http://testserver/?page=3', 'count': 50 } def test_setting_page_size(self): """ When 'paginate_by_param' is set, the client may choose a page size. """ request = factory.get('/', {'page_size': 10}) response = self.view(request) assert response.status_code == status.HTTP_200_OK assert response.data == { 'results': [2, 4, 6, 8, 10, 12, 14, 16, 18, 20], 'previous': None, 'next': 'http://testserver/?page=2&page_size=10', 'count': 50 } def test_setting_page_size_over_maximum(self): """ When page_size parameter exceeds maximum allowable, then it should be capped to the maximum. """ request = factory.get('/', {'page_size': 1000}) response = self.view(request) assert response.status_code == status.HTTP_200_OK assert response.data == { 'results': [ 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40 ], 'previous': None, 'next': 'http://testserver/?page=2&page_size=1000', 'count': 50 } def test_setting_page_size_to_zero(self): """ When page_size parameter is invalid it should return to the default. """ request = factory.get('/', {'page_size': 0}) response = self.view(request) assert response.status_code == status.HTTP_200_OK assert response.data == { 'results': [2, 4, 6, 8, 10], 'previous': None, 'next': 'http://testserver/?page=2&page_size=0', 'count': 50 } def test_additional_query_params_are_preserved(self): request = factory.get('/', {'page': 2, 'filter': 'even'}) response = self.view(request) assert response.status_code == status.HTTP_200_OK assert response.data == { 'results': [12, 14, 16, 18, 20], 'previous': 'http://testserver/?filter=even', 'next': 'http://testserver/?filter=even&page=3', 'count': 50 } def test_empty_query_params_are_preserved(self): request = factory.get('/', {'page': 2, 'filter': ''}) response = self.view(request) assert response.status_code == status.HTTP_200_OK assert response.data == { 'results': [12, 14, 16, 18, 20], 'previous': 'http://testserver/?filter=', 'next': 'http://testserver/?filter=&page=3', 'count': 50 } def test_404_not_found_for_zero_page(self): request = factory.get('/', {'page': '0'}) response = self.view(request) assert response.status_code == status.HTTP_404_NOT_FOUND assert response.data == { 'detail': 'Invalid page.' } def test_404_not_found_for_invalid_page(self): request = factory.get('/', {'page': 'invalid'}) response = self.view(request) assert response.status_code == status.HTTP_404_NOT_FOUND assert response.data == { 'detail': 'Invalid page.' } class TestPaginationDisabledIntegration: """ Integration tests for disabled pagination. """ def setup(self): class PassThroughSerializer(serializers.BaseSerializer): def to_representation(self, item): return item self.view = generics.ListAPIView.as_view( serializer_class=PassThroughSerializer, queryset=range(1, 101), pagination_class=None ) def test_unpaginated_list(self): request = factory.get('/', {'page': 2}) response = self.view(request) assert response.status_code == status.HTTP_200_OK assert response.data == list(range(1, 101)) class TestPageNumberPagination: """ Unit tests for `pagination.PageNumberPagination`. """ def setup(self): class ExamplePagination(pagination.PageNumberPagination): page_size = 5 self.pagination = ExamplePagination() self.queryset = range(1, 101) def paginate_queryset(self, request): return list(self.pagination.paginate_queryset(self.queryset, request)) def get_paginated_content(self, queryset): response = self.pagination.get_paginated_response(queryset) return response.data def get_html_context(self): return self.pagination.get_html_context() def test_no_page_number(self): request = Request(factory.get('/')) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) context = self.get_html_context() assert queryset == [1, 2, 3, 4, 5] assert content == { 'results': [1, 2, 3, 4, 5], 'previous': None, 'next': 'http://testserver/?page=2', 'count': 100 } assert context == { 'previous_url': None, 'next_url': 'http://testserver/?page=2', 'page_links': [ PageLink('http://testserver/', 1, True, False), PageLink('http://testserver/?page=2', 2, False, False), PageLink('http://testserver/?page=3', 3, False, False), PAGE_BREAK, PageLink('http://testserver/?page=20', 20, False, False), ] } assert self.pagination.display_page_controls assert isinstance(self.pagination.to_html(), type('')) def test_second_page(self): request = Request(factory.get('/', {'page': 2})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) context = self.get_html_context() assert queryset == [6, 7, 8, 9, 10] assert content == { 'results': [6, 7, 8, 9, 10], 'previous': 'http://testserver/', 'next': 'http://testserver/?page=3', 'count': 100 } assert context == { 'previous_url': 'http://testserver/', 'next_url': 'http://testserver/?page=3', 'page_links': [ PageLink('http://testserver/', 1, False, False), PageLink('http://testserver/?page=2', 2, True, False), PageLink('http://testserver/?page=3', 3, False, False), PAGE_BREAK, PageLink('http://testserver/?page=20', 20, False, False), ] } def test_last_page(self): request = Request(factory.get('/', {'page': 'last'})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) context = self.get_html_context() assert queryset == [96, 97, 98, 99, 100] assert content == { 'results': [96, 97, 98, 99, 100], 'previous': 'http://testserver/?page=19', 'next': None, 'count': 100 } assert context == { 'previous_url': 'http://testserver/?page=19', 'next_url': None, 'page_links': [ PageLink('http://testserver/', 1, False, False), PAGE_BREAK, PageLink('http://testserver/?page=18', 18, False, False), PageLink('http://testserver/?page=19', 19, False, False), PageLink('http://testserver/?page=20', 20, True, False), ] } def test_invalid_page(self): request = Request(factory.get('/', {'page': 'invalid'})) with pytest.raises(exceptions.NotFound): self.paginate_queryset(request) class TestPageNumberPaginationOverride: """ Unit tests for `pagination.PageNumberPagination`. the Django Paginator Class is overridden. """ def setup(self): class OverriddenDjangoPaginator(DjangoPaginator): # override the count in our overridden Django Paginator # we will only return one page, with one item count = 1 class ExamplePagination(pagination.PageNumberPagination): django_paginator_class = OverriddenDjangoPaginator page_size = 5 self.pagination = ExamplePagination() self.queryset = range(1, 101) def paginate_queryset(self, request): return list(self.pagination.paginate_queryset(self.queryset, request)) def get_paginated_content(self, queryset): response = self.pagination.get_paginated_response(queryset) return response.data def get_html_context(self): return self.pagination.get_html_context() def test_no_page_number(self): request = Request(factory.get('/')) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) context = self.get_html_context() assert queryset == [1] assert content == { 'results': [1, ], 'previous': None, 'next': None, 'count': 1 } assert context == { 'previous_url': None, 'next_url': None, 'page_links': [ PageLink('http://testserver/', 1, True, False), ] } assert not self.pagination.display_page_controls assert isinstance(self.pagination.to_html(), type('')) def test_invalid_page(self): request = Request(factory.get('/', {'page': 'invalid'})) with pytest.raises(exceptions.NotFound): self.paginate_queryset(request) class TestLimitOffset: """ Unit tests for `pagination.LimitOffsetPagination`. """ def setup(self): class ExamplePagination(pagination.LimitOffsetPagination): default_limit = 10 max_limit = 15 self.pagination = ExamplePagination() self.queryset = range(1, 101) def paginate_queryset(self, request): return list(self.pagination.paginate_queryset(self.queryset, request)) def get_paginated_content(self, queryset): response = self.pagination.get_paginated_response(queryset) return response.data def get_html_context(self): return self.pagination.get_html_context() def test_no_offset(self): request = Request(factory.get('/', {'limit': 5})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) context = self.get_html_context() assert queryset == [1, 2, 3, 4, 5] assert content == { 'results': [1, 2, 3, 4, 5], 'previous': None, 'next': 'http://testserver/?limit=5&offset=5', 'count': 100 } assert context == { 'previous_url': None, 'next_url': 'http://testserver/?limit=5&offset=5', 'page_links': [ PageLink('http://testserver/?limit=5', 1, True, False), PageLink('http://testserver/?limit=5&offset=5', 2, False, False), PageLink('http://testserver/?limit=5&offset=10', 3, False, False), PAGE_BREAK, PageLink('http://testserver/?limit=5&offset=95', 20, False, False), ] } assert self.pagination.display_page_controls assert isinstance(self.pagination.to_html(), type('')) def test_pagination_not_applied_if_limit_or_default_limit_not_set(self): class MockPagination(pagination.LimitOffsetPagination): default_limit = None request = Request(factory.get('/')) queryset = MockPagination().paginate_queryset(self.queryset, request) assert queryset is None def test_single_offset(self): """ When the offset is not a multiple of the limit we get some edge cases: * The first page should still be offset zero. * We may end up displaying an extra page in the pagination control. """ request = Request(factory.get('/', {'limit': 5, 'offset': 1})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) context = self.get_html_context() assert queryset == [2, 3, 4, 5, 6] assert content == { 'results': [2, 3, 4, 5, 6], 'previous': 'http://testserver/?limit=5', 'next': 'http://testserver/?limit=5&offset=6', 'count': 100 } assert context == { 'previous_url': 'http://testserver/?limit=5', 'next_url': 'http://testserver/?limit=5&offset=6', 'page_links': [ PageLink('http://testserver/?limit=5', 1, False, False), PageLink('http://testserver/?limit=5&offset=1', 2, True, False), PageLink('http://testserver/?limit=5&offset=6', 3, False, False), PAGE_BREAK, PageLink('http://testserver/?limit=5&offset=96', 21, False, False), ] } def test_first_offset(self): request = Request(factory.get('/', {'limit': 5, 'offset': 5})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) context = self.get_html_context() assert queryset == [6, 7, 8, 9, 10] assert content == { 'results': [6, 7, 8, 9, 10], 'previous': 'http://testserver/?limit=5', 'next': 'http://testserver/?limit=5&offset=10', 'count': 100 } assert context == { 'previous_url': 'http://testserver/?limit=5', 'next_url': 'http://testserver/?limit=5&offset=10', 'page_links': [ PageLink('http://testserver/?limit=5', 1, False, False), PageLink('http://testserver/?limit=5&offset=5', 2, True, False), PageLink('http://testserver/?limit=5&offset=10', 3, False, False), PAGE_BREAK, PageLink('http://testserver/?limit=5&offset=95', 20, False, False), ] } def test_middle_offset(self): request = Request(factory.get('/', {'limit': 5, 'offset': 10})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) context = self.get_html_context() assert queryset == [11, 12, 13, 14, 15] assert content == { 'results': [11, 12, 13, 14, 15], 'previous': 'http://testserver/?limit=5&offset=5', 'next': 'http://testserver/?limit=5&offset=15', 'count': 100 } assert context == { 'previous_url': 'http://testserver/?limit=5&offset=5', 'next_url': 'http://testserver/?limit=5&offset=15', 'page_links': [ PageLink('http://testserver/?limit=5', 1, False, False), PageLink('http://testserver/?limit=5&offset=5', 2, False, False), PageLink('http://testserver/?limit=5&offset=10', 3, True, False), PageLink('http://testserver/?limit=5&offset=15', 4, False, False), PAGE_BREAK, PageLink('http://testserver/?limit=5&offset=95', 20, False, False), ] } def test_ending_offset(self): request = Request(factory.get('/', {'limit': 5, 'offset': 95})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) context = self.get_html_context() assert queryset == [96, 97, 98, 99, 100] assert content == { 'results': [96, 97, 98, 99, 100], 'previous': 'http://testserver/?limit=5&offset=90', 'next': None, 'count': 100 } assert context == { 'previous_url': 'http://testserver/?limit=5&offset=90', 'next_url': None, 'page_links': [ PageLink('http://testserver/?limit=5', 1, False, False), PAGE_BREAK, PageLink('http://testserver/?limit=5&offset=85', 18, False, False), PageLink('http://testserver/?limit=5&offset=90', 19, False, False), PageLink('http://testserver/?limit=5&offset=95', 20, True, False), ] } def test_erronous_offset(self): request = Request(factory.get('/', {'limit': 5, 'offset': 1000})) queryset = self.paginate_queryset(request) self.get_paginated_content(queryset) self.get_html_context() def test_invalid_offset(self): """ An invalid offset query param should be treated as 0. """ request = Request(factory.get('/', {'limit': 5, 'offset': 'invalid'})) queryset = self.paginate_queryset(request) assert queryset == [1, 2, 3, 4, 5] def test_invalid_limit(self): """ An invalid limit query param should be ignored in favor of the default. """ request = Request(factory.get('/', {'limit': 'invalid', 'offset': 0})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) next_limit = self.pagination.default_limit next_offset = self.pagination.default_limit next_url = 'http://testserver/?limit={0}&offset={1}'.format(next_limit, next_offset) assert queryset == [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] assert content.get('next') == next_url def test_zero_limit(self): """ An zero limit query param should be ignored in favor of the default. """ request = Request(factory.get('/', {'limit': 0, 'offset': 0})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) next_limit = self.pagination.default_limit next_offset = self.pagination.default_limit next_url = 'http://testserver/?limit={0}&offset={1}'.format(next_limit, next_offset) assert queryset == [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] assert content.get('next') == next_url def test_max_limit(self): """ The limit defaults to the max_limit when there is a max_limit and the requested limit is greater than the max_limit """ offset = 50 request = Request(factory.get('/', {'limit': '11235', 'offset': offset})) queryset = self.paginate_queryset(request) content = self.get_paginated_content(queryset) max_limit = self.pagination.max_limit next_offset = offset + max_limit prev_offset = offset - max_limit base_url = 'http://testserver/?limit={0}'.format(max_limit) next_url = base_url + '&offset={0}'.format(next_offset) prev_url = base_url + '&offset={0}'.format(prev_offset) assert queryset == list(range(51, 66)) assert content.get('next') == next_url assert content.get('previous') == prev_url class CursorPaginationTestsMixin: def test_invalid_cursor(self): request = Request(factory.get('/', {'cursor': '123'})) with pytest.raises(exceptions.NotFound): self.pagination.paginate_queryset(self.queryset, request) def test_use_with_ordering_filter(self): class MockView: filter_backends = (filters.OrderingFilter,) ordering_fields = ['username', 'created'] ordering = 'created' request = Request(factory.get('/', {'ordering': 'username'})) ordering = self.pagination.get_ordering(request, [], MockView()) assert ordering == ('username',) request = Request(factory.get('/', {'ordering': '-username'})) ordering = self.pagination.get_ordering(request, [], MockView()) assert ordering == ('-username',) request = Request(factory.get('/', {'ordering': 'invalid'})) ordering = self.pagination.get_ordering(request, [], MockView()) assert ordering == ('created',) def test_cursor_pagination(self): (previous, current, next, previous_url, next_url) = self.get_pages('/') assert previous is None assert current == [1, 1, 1, 1, 1] assert next == [1, 2, 3, 4, 4] (previous, current, next, previous_url, next_url) = self.get_pages(next_url) assert previous == [1, 1, 1, 1, 1] assert current == [1, 2, 3, 4, 4] assert next == [4, 4, 5, 6, 7] (previous, current, next, previous_url, next_url) = self.get_pages(next_url) assert previous == [1, 2, 3, 4, 4] assert current == [4, 4, 5, 6, 7] assert next == [7, 7, 7, 7, 7] (previous, current, next, previous_url, next_url) = self.get_pages(next_url) assert previous == [4, 4, 4, 5, 6] # Paging artifact assert current == [7, 7, 7, 7, 7] assert next == [7, 7, 7, 8, 9] (previous, current, next, previous_url, next_url) = self.get_pages(next_url) assert previous == [7, 7, 7, 7, 7] assert current == [7, 7, 7, 8, 9] assert next == [9, 9, 9, 9, 9] (previous, current, next, previous_url, next_url) = self.get_pages(next_url) assert previous == [7, 7, 7, 8, 9] assert current == [9, 9, 9, 9, 9] assert next is None (previous, current, next, previous_url, next_url) = self.get_pages(previous_url) assert previous == [7, 7, 7, 7, 7] assert current == [7, 7, 7, 8, 9] assert next == [9, 9, 9, 9, 9] (previous, current, next, previous_url, next_url) = self.get_pages(previous_url) assert previous == [4, 4, 5, 6, 7] assert current == [7, 7, 7, 7, 7] assert next == [8, 9, 9, 9, 9] # Paging artifact (previous, current, next, previous_url, next_url) = self.get_pages(previous_url) assert previous == [1, 2, 3, 4, 4] assert current == [4, 4, 5, 6, 7] assert next == [7, 7, 7, 7, 7] (previous, current, next, previous_url, next_url) = self.get_pages(previous_url) assert previous == [1, 1, 1, 1, 1] assert current == [1, 2, 3, 4, 4] assert next == [4, 4, 5, 6, 7] (previous, current, next, previous_url, next_url) = self.get_pages(previous_url) assert previous is None assert current == [1, 1, 1, 1, 1] assert next == [1, 2, 3, 4, 4] assert isinstance(self.pagination.to_html(), type('')) class TestCursorPagination(CursorPaginationTestsMixin): """ Unit tests for `pagination.CursorPagination`. """ def setup(self): class MockObject(object): def __init__(self, idx): self.created = idx class MockQuerySet(object): def __init__(self, items): self.items = items def filter(self, created__gt=None, created__lt=None): if created__gt is not None: return MockQuerySet([ item for item in self.items if item.created > int(created__gt) ]) assert created__lt is not None return MockQuerySet([ item for item in self.items if item.created < int(created__lt) ]) def order_by(self, *ordering): if ordering[0].startswith('-'): return MockQuerySet(list(reversed(self.items))) return self def __getitem__(self, sliced): return self.items[sliced] class ExamplePagination(pagination.CursorPagination): page_size = 5 ordering = 'created' self.pagination = ExamplePagination() self.queryset = MockQuerySet([ MockObject(idx) for idx in [ 1, 1, 1, 1, 1, 1, 2, 3, 4, 4, 4, 4, 5, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 9, 9, 9, 9, 9, 9 ] ]) def get_pages(self, url): """ Given a URL return a tuple of: (previous page, current page, next page, previous url, next url) """ request = Request(factory.get(url)) queryset = self.pagination.paginate_queryset(self.queryset, request) current = [item.created for item in queryset] next_url = self.pagination.get_next_link() previous_url = self.pagination.get_previous_link() if next_url is not None: request = Request(factory.get(next_url)) queryset = self.pagination.paginate_queryset(self.queryset, request) next = [item.created for item in queryset] else: next = None if previous_url is not None: request = Request(factory.get(previous_url)) queryset = self.pagination.paginate_queryset(self.queryset, request) previous = [item.created for item in queryset] else: previous = None return (previous, current, next, previous_url, next_url) class CursorPaginationModel(models.Model): created = models.IntegerField() class TestCursorPaginationWithValueQueryset(CursorPaginationTestsMixin, TestCase): """ Unit tests for `pagination.CursorPagination` for value querysets. """ def setUp(self): class ExamplePagination(pagination.CursorPagination): page_size = 5 ordering = 'created' self.pagination = ExamplePagination() data = [ 1, 1, 1, 1, 1, 1, 2, 3, 4, 4, 4, 4, 5, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 9, 9, 9, 9, 9, 9 ] for idx in data: CursorPaginationModel.objects.create(created=idx) self.queryset = CursorPaginationModel.objects.values() def get_pages(self, url): """ Given a URL return a tuple of: (previous page, current page, next page, previous url, next url) """ request = Request(factory.get(url)) queryset = self.pagination.paginate_queryset(self.queryset, request) current = [item['created'] for item in queryset] next_url = self.pagination.get_next_link() previous_url = self.pagination.get_previous_link() if next_url is not None: request = Request(factory.get(next_url)) queryset = self.pagination.paginate_queryset(self.queryset, request) next = [item['created'] for item in queryset] else: next = None if previous_url is not None: request = Request(factory.get(previous_url)) queryset = self.pagination.paginate_queryset(self.queryset, request) previous = [item['created'] for item in queryset] else: previous = None return (previous, current, next, previous_url, next_url) def test_get_displayed_page_numbers(): """ Test our contextual page display function. This determines which pages to display in a pagination control, given the current page and the last page. """ displayed_page_numbers = pagination._get_displayed_page_numbers # At five pages or less, all pages are displayed, always. assert displayed_page_numbers(1, 5) == [1, 2, 3, 4, 5] assert displayed_page_numbers(2, 5) == [1, 2, 3, 4, 5] assert displayed_page_numbers(3, 5) == [1, 2, 3, 4, 5] assert displayed_page_numbers(4, 5) == [1, 2, 3, 4, 5] assert displayed_page_numbers(5, 5) == [1, 2, 3, 4, 5] # Between six and either pages we may have a single page break. assert displayed_page_numbers(1, 6) == [1, 2, 3, None, 6] assert displayed_page_numbers(2, 6) == [1, 2, 3, None, 6] assert displayed_page_numbers(3, 6) == [1, 2, 3, 4, 5, 6] assert displayed_page_numbers(4, 6) == [1, 2, 3, 4, 5, 6] assert displayed_page_numbers(5, 6) == [1, None, 4, 5, 6] assert displayed_page_numbers(6, 6) == [1, None, 4, 5, 6] assert displayed_page_numbers(1, 7) == [1, 2, 3, None, 7] assert displayed_page_numbers(2, 7) == [1, 2, 3, None, 7] assert displayed_page_numbers(3, 7) == [1, 2, 3, 4, None, 7] assert displayed_page_numbers(4, 7) == [1, 2, 3, 4, 5, 6, 7] assert displayed_page_numbers(5, 7) == [1, None, 4, 5, 6, 7] assert displayed_page_numbers(6, 7) == [1, None, 5, 6, 7] assert displayed_page_numbers(7, 7) == [1, None, 5, 6, 7] assert displayed_page_numbers(1, 8) == [1, 2, 3, None, 8] assert displayed_page_numbers(2, 8) == [1, 2, 3, None, 8] assert displayed_page_numbers(3, 8) == [1, 2, 3, 4, None, 8] assert displayed_page_numbers(4, 8) == [1, 2, 3, 4, 5, None, 8] assert displayed_page_numbers(5, 8) == [1, None, 4, 5, 6, 7, 8] assert displayed_page_numbers(6, 8) == [1, None, 5, 6, 7, 8] assert displayed_page_numbers(7, 8) == [1, None, 6, 7, 8] assert displayed_page_numbers(8, 8) == [1, None, 6, 7, 8] # At nine or more pages we may have two page breaks, one on each side. assert displayed_page_numbers(1, 9) == [1, 2, 3, None, 9] assert displayed_page_numbers(2, 9) == [1, 2, 3, None, 9] assert displayed_page_numbers(3, 9) == [1, 2, 3, 4, None, 9] assert displayed_page_numbers(4, 9) == [1, 2, 3, 4, 5, None, 9] assert displayed_page_numbers(5, 9) == [1, None, 4, 5, 6, None, 9] assert displayed_page_numbers(6, 9) == [1, None, 5, 6, 7, 8, 9] assert displayed_page_numbers(7, 9) == [1, None, 6, 7, 8, 9] assert displayed_page_numbers(8, 9) == [1, None, 7, 8, 9] assert displayed_page_numbers(9, 9) == [1, None, 7, 8, 9]