Send email to admin on new user signup

bats_ai/core/models/user_profile.py

@@ -1,7 +1,10 @@
 from django.contrib.auth.models import User
+from django.contrib.sites.models import Site
+from django.core.mail import send_mail
 from django.db import models
 from django.db.models.signals import post_save
 from django.dispatch import receiver
+from django.template.loader import render_to_string
 
 
 class UserProfile(models.Model):
@@ -13,3 +16,25 @@ class UserProfile(models.Model):
 def _create_new_user_profile(sender, instance, created, **kwargs):
     if created:
         UserProfile.objects.create(user=instance)
+
+
+@receiver(post_save, sender=User)
+def _notify_admins_new_user(sender, instance, created, **kwargs):
+    admins = User.objects.filter(is_superuser=True)
+    current_site = Site.objects.get_current()
+    recipient_list = [admin.email for admin in admins]
+
+    if recipient_list:
+        email_content = render_to_string(
+            'core/new_user_signup.txt',
+            {
+                'user': instance,
+                'site': current_site,
+            },
+        )
+        send_mail(
+            subject=f'{current_site.name}: New user signup',
+            message=email_content,
+            from_email=None,
+            recipient_list=recipient_list,
+        )

bats_ai/core/templates/core/new_user_signup.txt

@@ -0,0 +1,5 @@
+This is an automated notification from {{ site.name }} to alert admins that a new user {{ user.email }} has signed up.
+
+To see additional details about the user, and take actions like verifying the user's profile, go to
+
+https://{{ site.domain }}{% url 'admin:auth_user_change' user.pk %}

bats_ai/core/tests/test_user_profile.py

@@ -1,8 +1,11 @@
 from django.contrib.auth.models import User
+from django.urls import reverse
 import pytest
 
 from bats_ai.core.models import UserProfile
 
+from .factories import SuperuserFactory
+
 
 @pytest.mark.django_db
 def test_profile_creation():
@@ -11,3 +14,16 @@ def test_profile_creation():
     user = User.objects.create()
     profile = UserProfile.objects.get(user=user)
     assert not profile.verified
+
+
+@pytest.mark.django_db
+def test_new_user_signup_email_sent(mailoutbox):
+    superuser = SuperuserFactory()
+    new_user = User.objects.create(
+        username='foo',
+        email='foo@bar.com',
+    )
+    message = next(filter(lambda message: 'New user signup' in message.subject, mailoutbox), None)
+    assert message is not None
+    assert superuser.email in message.to
+    assert reverse('admin:auth_user_change', args=[new_user.pk]) in message.body