Add email verification feature (#21672)

* feat(): disable devhub.verify_email without waffle switch

* chore(devhub): migration - add suppress-email waffle switch + docs

docs/topics/development/index.rst

@@ -19,4 +19,5 @@ Development
    translations
    search
    docs
+   waffle
    ../../../README.rst

docs/topics/development/waffle.md

@@ -0,0 +1,133 @@
+# Waffle
+
+We use [waffle](https://waffle.readthedocs.io/en/stable/) for managing feature access in production.
+
+## Why switches and not flags
+
+We prefer to use [switches](https://waffle.readthedocs.io/en/stable/types/switch.html)
+over flags in most cases as switches are:
+
+- switches are simple
+- switches are easy to reason about
+
+Flags can be used if you want to do a gradual rollout a feature over time or to a subset of users.
+
+We have a flag `2fa-enforcement-for-developers-and-special-users` in production now.
+
+## Creating/Deleting a switch
+
+Switches are added via database migrations.
+This ensures the switch exists in all environments once the migration is run.
+
+To create or remove a switch,
+first create an empty migration in the app where your switch will live.
+
+```bash
+python ./manage.py makemigrations <app> --empty
+```
+
+### Creating a switch
+
+add the switch in the migration
+
+```python
+from django.db import migrations
+
+from olympia.core.db.migrations import CreateWaffleSwitch
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('app', '0001_auto_20220531_2434'),
+    ]
+
+    operations = [
+        CreateWaffleSwitch('foo')
+    ]
+```
+
+### Deleting a switch
+
+remove the switch in the migration
+
+```python
+
+from django.db import migrations
+
+from olympia.core.db.migrations import DeleteWaffleSwitch
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('app', '0001_auto_20220531_2434'),
+    ]
+
+    operations = [
+        DeleteWaffleSwitch('foo')
+    ]
+```
+
+## Using a switch
+
+Use your switch in python code
+
+```python
+if waffle.switch_is_active('foo'):
+    # do something
+```
+
+Use your switch in jinja2
+
+```django
+{% if waffle.switch_is_active('foo') %}
+    <p>foo is active</p>
+{% endif %}
+```
+
+## Testing
+
+Testing the result of a switch being on or off is important
+to ensure your switch behaves appropriately. We can override the value of a switch easily.
+
+Override for an entire test case
+
+```python
+# Override an entire test case class
+@override_switch('foo', active=True)
+class TestFoo(TestCase):
+    def test_bar(self):
+        assert waffle.switch_is_active('foo')
+
+    # Override an individual test method
+    @override_switch('foo', active=False)
+    def test_baz(self):
+        assert not waffle.switch_is_active('foo')
+```
+
+## Enabling your switch
+
+Once your switch is deployed, you can enable it in a given environment by following these steps.
+
+1. ssh into a kubernetes pod in the environment you want to enable the switch in. ([instructions][devops])
+2. run the CLI command to enable your switch ([instructions][waffle-cli])
+
+Toggling a switch on
+
+```bash
+./manage.py waffle_switch foo on
+```
+
+Once you've ensured that it works on dev, the typical way of doing things would be to add that manage.py command
+to the deploy instructions for the relevant tag.
+The engineer responsible for the tag would run the command on stage,
+then SRE would run it in production on deploy.
+
+## Cleanup
+
+After a switch is enabled for all users and is no longer needed, you can remove it by:
+
+1. Deleting all code referring to the switch.
+2. adding a migration to remove the flag.
+
+[devops]: https://mozilla-hub.atlassian.net/wiki/spaces/FDPDT/pages/98795521/DevOps#How-to-run-./manage.py-commands-in-an-environment "Devops"
+[waffle-cli]: https://waffle.readthedocs.io/en/stable/usage/cli.html#switches "Waffle CLI"

src/olympia/devhub/migrations/0006_auto_20240109_1118.py

@@ -0,0 +1,15 @@
+# Generated by Django 4.2.8 on 2024-01-09 11:18
+
+from django.db import migrations
+
+from olympia.core.db.migrations import CreateWaffleSwitch
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('devhub', '0005_auto_20220531_1043'),
+    ]
+
+    operations = [
+        CreateWaffleSwitch('suppressed-email')
+    ]

src/olympia/devhub/tests/test_views.py

@@ -2184,6 +2184,7 @@ def test_link_to_stats_for_dictionaries(self):
         )
 
 
+@override_switch('suppressed-email', active=True)
 class TestVerifyEmail(TestCase):
     def setUp(self):
         super().setUp()
@@ -2238,6 +2239,16 @@ def _assert_redirect_self(self, response, url=None):
         url = self.url if url is None else url
         self.assert3xx(response, url)
 
+    @override_switch('suppressed-email', active=False)
+    def test_suppressed_email_waffle_disabled(self):
+        self._create_suppressed_email(self.user_profile)
+
+        assert self.user_profile.suppressed_email
+
+        response = self._get()
+
+        self.assert3xx(response, reverse('devhub.addons'))
+
     def test_hide_suppressed_email_snippet(self):
         """
         on verification page, do not show the suppressed email snippet

src/olympia/devhub/views.py

@@ -2114,6 +2114,9 @@ def email_verification(request):
     email_verification = request.user.email_verification
     suppressed_email = request.user.suppressed_email
 
+    if not waffle.switch_is_active('suppressed-email'):
+        return redirect('devhub.addons')
+
     if request.method == 'POST':
         if email_verification:
             email_verification.delete()