Add pagination (#63)

* Add pagination tag (#11)

* Add pagination tag tests (#11)

* Improve styling (#11)

bookmarks/tests/test_pagination_tag.py

@@ -0,0 +1,117 @@
+from django.core.paginator import Paginator
+from django.test import SimpleTestCase, RequestFactory
+from django.template import Template, RequestContext
+
+
+class PaginationTagTest(SimpleTestCase):
+
+    def render_template(self, num_items: int, page_size: int, current_page: int, url: str = '/test') -> str:
+        rf = RequestFactory()
+        request = rf.get(url)
+        paginator = Paginator(range(0, num_items), page_size)
+        page = paginator.page(current_page)
+
+        context = RequestContext(request, {'page': page})
+        template_to_render = Template(
+            '{% load pagination %}'
+            '{% pagination page %}'
+        )
+        return template_to_render.render(context)
+
+    def assertPrevLinkDisabled(self, html: str):
+        self.assertInHTML('''
+            <li class="page-item disabled">
+                <a href="#" tabindex="-1">Previous</a>
+            </li>
+            ''', html)
+
+    def assertPrevLink(self, html: str, page_number: int, href: str = None):
+        href = href if href else '?page={0}'.format(page_number)
+        self.assertInHTML('''
+            <li class="page-item">
+                <a href="{0}" tabindex="-1">Previous</a>
+            </li>
+            '''.format(href), html)
+
+    def assertNextLinkDisabled(self, html: str):
+        self.assertInHTML('''
+            <li class="page-item disabled">
+                <a href="#" tabindex="-1">Next</a>
+            </li>
+            ''', html)
+
+    def assertNextLink(self, html: str, page_number: int, href: str = None):
+        href = href if href else '?page={0}'.format(page_number)
+        self.assertInHTML('''
+            <li class="page-item">
+                <a href="{0}" tabindex="-1">Next</a>
+            </li>
+            '''.format(href), html)
+
+    def assertPageLink(self, html: str, page_number: int, active: bool, count: int = 1, href: str = None):
+        active_class = 'active' if active else ''
+        href = href if href else '?page={0}'.format(page_number)
+        self.assertInHTML('''
+            <li class="page-item {1}">
+                <a href="{2}">{0}</a>
+            </li>
+            '''.format(page_number, active_class, href), html, count=count)
+
+    def assertTruncationIndicators(self, html: str, count: int):
+        self.assertInHTML('''
+            <li class="page-item">
+                <span>...</span>
+            </li>
+            ''', html, count=count)
+
+    def test_previous_disabled_on_page_1(self):
+        rendered_template = self.render_template(100, 10, 1)
+        self.assertPrevLinkDisabled(rendered_template)
+
+    def test_previous_enabled_after_page_1(self):
+        for page_number in range(2, 10):
+            rendered_template = self.render_template(100, 10, page_number)
+            self.assertPrevLink(rendered_template, page_number - 1)
+
+    def test_next_disabled_on_last_page(self):
+        rendered_template = self.render_template(100, 10, 10)
+        self.assertNextLinkDisabled(rendered_template)
+
+    def test_next_enabled_before_last_page(self):
+        for page_number in range(1, 9):
+            rendered_template = self.render_template(100, 10, page_number)
+            self.assertNextLink(rendered_template, page_number + 1)
+
+    def test_truncate_pages_start(self):
+        current_page = 1
+        expected_visible_pages = [1, 2, 3, 10]
+        rendered_template = self.render_template(100, 10, current_page)
+        for page_number in range(1, 10):
+            expected_occurrences = 1 if page_number in expected_visible_pages else 0
+            self.assertPageLink(rendered_template, page_number, page_number == current_page, expected_occurrences)
+        self.assertTruncationIndicators(rendered_template, 1)
+
+    def test_truncate_pages_middle(self):
+        current_page = 5
+        expected_visible_pages = [1, 3, 4, 5, 6, 7, 10]
+        rendered_template = self.render_template(100, 10, current_page)
+        for page_number in range(1, 10):
+            expected_occurrences = 1 if page_number in expected_visible_pages else 0
+            self.assertPageLink(rendered_template, page_number, page_number == current_page, expected_occurrences)
+        self.assertTruncationIndicators(rendered_template, 2)
+
+    def test_truncate_pages_near_end(self):
+        current_page = 9
+        expected_visible_pages = [1, 7, 8, 9, 10]
+        rendered_template = self.render_template(100, 10, current_page)
+        for page_number in range(1, 10):
+            expected_occurrences = 1 if page_number in expected_visible_pages else 0
+            self.assertPageLink(rendered_template, page_number, page_number == current_page, expected_occurrences)
+        self.assertTruncationIndicators(rendered_template, 1)
+
+    def test_extend_existing_query(self):
+        rendered_template = self.render_template(100, 10, 2, url='/test?q=cake')
+        self.assertPrevLink(rendered_template, 1, href='?q=cake&page=1')
+        self.assertPageLink(rendered_template, 1, False, href='?q=cake&page=1')
+        self.assertPageLink(rendered_template, 2, True, href='?q=cake&page=2')
+        self.assertNextLink(rendered_template, 3, href='?q=cake&page=3')