🪲 Fix pagination links (#6075)

The pagination links in various pages were using `url_for('programs_page')`, which builds a URL to a route on the global `app` object.

Since #6052 we don't have a global app object anymore. Instead, we use a global Blueprint called `app` instead.

In this PR, make all `url_for` calls in the same `app.py` file Blueprint-relative by prepending a period: `url_for('.programs_page')`, and make the `url_for` in the teachers page that points to a user's programs page (probably legacy and unused?) absolute by prepending the full Blueprint name: `url_for('app.programs_page')`.

Add tests to make sure that the page renders successfully.

**How to test**

Automatic tests have been added, so if they pass we should be good.

app.py

@@ -1126,9 +1126,9 @@ def programs_page(user):
     sorted_adventure_programs = hedy_content.Adventures(g.lang) \
         .get_sorted_adventure_programs(all_programs, adventure_names)
 
-    next_page_url = url_for('programs_page', **dict(request.args, page=result.next_page_token)
+    next_page_url = url_for('.programs_page', **dict(request.args, page=result.next_page_token)
                             ) if result.next_page_token else None
-    prev_page_url = url_for('programs_page', **dict(request.args, page=result.prev_page_token)
+    prev_page_url = url_for('.programs_page', **dict(request.args, page=result.prev_page_token)
                             ) if result.prev_page_token else None
 
     return render_template(
@@ -2473,9 +2473,9 @@ def explore():
         language_filter=language,
         adventure_filter=adventure,
         pagination_token=page)
-    next_page_url = url_for('explore', **dict(request.args, page=result.next_page_token)
+    next_page_url = url_for('.explore', **dict(request.args, page=result.next_page_token)
                             ) if result.next_page_token else None
-    prev_page_url = url_for('explore', **dict(request.args, page=result.prev_page_token)
+    prev_page_url = url_for('.explore', **dict(request.args, page=result.prev_page_token)
                             ) if result.prev_page_token else None
 
     favourite_programs = g_db().get_hedy_choices()
@@ -2920,7 +2920,7 @@ def public_user_page(username):
         last_achieved = None
         certificate_message = safe_format(gettext('see_certificate'), username=username)
         next_page_url = url_for(
-            'public_user_page',
+            '.public_user_page',
             username=username, **dict(request.args,
                                       page=next_page_token)) if next_page_token else None
 
@@ -3158,7 +3158,7 @@ def on_offline_mode():
     debug = utils.is_debug_mode() and not (is_in_debugger or profile_memory)
     if debug:
         logger.debug('app starting in debug mode')
-    app_obj.add_url_rule("/", endpoint="index")
+
     # Threaded option enables multiple instances for multiple user access support
     app_obj.run(threaded=True, debug=debug,
                 port=config['port'], host="0.0.0.0")

templates/explore.html

@@ -4,14 +4,14 @@
     <div class="w-full mb-4" id="program_filter">
             <div class="flex flex-row w-full items-center rounded-lg gap-4">
                 <custom-select name="adventure" id="explore_page_adventure" data-autosubmit="true" class="w-2/3" data-type="single">
-                    <option hidden 
-                        {% if not filtered_adventure %} selected{% endif %} 
+                    <option hidden
+                        {% if not filtered_adventure %} selected{% endif %}
                         value=""
                         hx-get="/explore?level={{ filtered_level }}"
                         hx-target="#main_container">{{ _('adventure') }}</option>
                     {% for adventure_key, name in adventures_names.items() %}
-                        <option hidden 
-                            value="{{ adventure_key }}" 
+                        <option hidden
+                            value="{{ adventure_key }}"
                             {% if adventure_key == filtered_adventure %}selected{% endif %}
                             hx-get="/explore?adventure={{ adventure_key }}&level={{ filtered_level }}"
                             hx-target="#main_container">{{ name }}</option>
@@ -55,10 +55,10 @@ <h2 class="text-center z-10 font-bold pb-0 mb-0 text-3xl">{{_('hedy_choice_title
             </div>
             <div class="flex w-1/3 gap-4 align-self-right">
                 {% if prev_page_url %}
-                        <a href="{{prev_page_url}}" class="btn green-btn">{{_('previous_page')}}</a>
+                        <a href="{{prev_page_url}}" class="btn green-btn" aria-label="Previous page">{{_('previous_page')}}</a>
                 {% endif %}
                 {% if next_page_url %}
-                        <a href="{{next_page_url}}" class="btn green-btn">{{_('next_page')}}</a>
+                        <a href="{{next_page_url}}" class="btn green-btn" aria-label="Next page">{{_('next_page')}}</a>
                 {% endif %}
             </div>
         </div>

tests/python_html/fixtures/given.py

@@ -6,6 +6,16 @@
 from website.database import Database
 from website import auth
 import pytest
+import utils
+
+
+def unique_id():
+    return str(uuid.uuid4())
+
+
+def now_javascript():
+    """Return the current time in milliseconds, or a faked time if configured."""
+    return utils.timems()
 
 
 class Given:
@@ -15,13 +25,14 @@ def __init__(self, client: Client, db: Database):
         self.client = client
         self.db = db
         self.student_ctr = 1
+        self.teacher_ctr = 1
 
     def a_student_account(self, username=None, password=None, teacher_username=None, language='en'):
         """Create a student account."""
         if username is None:
             username = f'student{self.student_ctr}'
             self.student_ctr += 1
-        password = password or str(uuid.uuid4())
+        password = password or unique_id()
         student = {
             'username': username,
             'password': password,
@@ -31,6 +42,25 @@ def a_student_account(self, username=None, password=None, teacher_username=None,
         auth.store_new_student_account(self.db, student, teacher_username)
         return {'username': username, 'password': password}
 
+    def a_teacher_account(self, username=None, password=None, teacher_username=None, language='en'):
+        """Create a student account."""
+        if username is None:
+            username = f'student{self.teacher_ctr}'
+            self.teacher_ctr += 1
+        password = password or unique_id()
+        username, hashed, _ = auth.prepare_user_db(username, password)
+        teacher = {
+            'username': username,
+            'password': hashed,
+            'language': language,
+            'keyword_language': language,
+            'is_teacher': 1,
+            'created': now_javascript(),
+            'last_login': now_javascript(),
+        }
+        self.db.store_user(teacher)
+        return {'username': username, 'password': password}
+
     def logged_in_as_student(self, username=None):
         """Make sure that we are logged in."""
         user = self.a_student_account(username)
@@ -40,6 +70,34 @@ def logged_in_as_student(self, username=None):
             'password': user['password'],
         }), content_type='application/json')
         assert response.status_code == 200
+        return user
+
+    def logged_in_as_teacher(self, username=None):
+        """Make sure that we are logged in as a teacher."""
+        user = self.a_teacher_account(username)
+
+        response = self.client.post('/auth/login', data=json.dumps({
+            'username': user['username'],
+            'password': user['password'],
+        }), content_type='application/json')
+        assert response.status_code == 200
+        return user
+
+    def some_saved_program(self, username, **kwargs):
+        """Save a program for the given user."""
+        program = {
+            'id': unique_id(),
+            'session': username,
+            'username': username,
+            'date': now_javascript(),
+            'lang': 'en',
+            'level': 1,
+            'code': 'print TestProgram',
+            'adventure_name': 'default',
+            'name': 'TestProgram',
+        }
+        program.update(**kwargs)
+        return self.db.store_program(program)
 
 
 @pytest.fixture()

tests/python_html/test_explore.py

@@ -0,0 +1,23 @@
+# https://werkzeug.palletsprojects.com/en/stable/test/
+from .fixtures.given import Given
+from .fixtures.flask import Client
+import bs4
+
+
+def test_explore_page_loads_with_lots_of_programs(client: Client, given: Given):
+    """Smoke test of the explore page, if there are enough programs for pagination."""
+    # GIVEN
+    user = given.logged_in_as_student()
+    for _ in range(50):
+        given.some_saved_program(user['username'], public=1)
+
+    # WHEN
+    response = client.get('/explore')
+
+    # THEN - it succeeds, renders a lot of adventures and a next button
+    soup = bs4.BeautifulSoup(response.data, 'html.parser')
+    adventures = soup.find_all('div', class_='adventure')
+    assert len(adventures) > 40
+
+    next_page_link = soup.find('a', {'aria-label': 'Next page'})
+    assert next_page_link

tests/python_html/test_login.py

@@ -1,7 +1,6 @@
 # https://werkzeug.palletsprojects.com/en/stable/test/
 from .fixtures.given import Given
 from .fixtures.flask import Client
-import json
 import pytest
 
 

tests/python_html/test_programs.py

@@ -0,0 +1,16 @@
+# https://werkzeug.palletsprojects.com/en/stable/test/
+from .fixtures.given import Given
+from .fixtures.flask import Client
+
+
+def test_programs_page_loads_with_lots_of_programs(client: Client, given: Given):
+    """Smoke test of the programs page, if there are enough programs for pagination."""
+    # GIVEN
+    user = given.logged_in_as_student()
+    for _ in range(20):
+        given.some_saved_program(user['username'])
+
+    # WHEN
+    client.get('/programs')
+
+    # THEN - it succeeds

website/for_teachers.py

@@ -729,7 +729,7 @@ def public_programs(self, user, class_id, username):
         keyword_lang = g.keyword_lang
         adventure_names = hedy_content.Adventures(g.lang).get_adventure_names(keyword_lang)
 
-        next_page_url = url_for('programs_page', **dict(request.args, page=result.next_page_token)
+        next_page_url = url_for('app.programs_page', **dict(request.args, page=result.next_page_token)
                                 ) if result.next_page_token else None
 
         return render_template(