Renamed main script and added test script (to separate concerns of testing vs combining transition domain migration scripts). Added test data files.

src/registrar/tests/test_transition_domain_migrations_with_logins.py

@@ -0,0 +1,42 @@
+from django.test import TestCase
+from django.db.utils import IntegrityError
+from unittest.mock import patch
+
+from registrar.models import (
+    Contact,
+    DomainApplication,
+    DomainInformation,
+    User,
+    Website,
+    Domain,
+    DraftDomain,
+    DomainInvitation,
+    UserDomainRole,
+)
+
+import boto3_mocking  # type: ignore
+from .common import MockSESClient, less_console_noise, completed_application
+from django_fsm import TransitionNotAllowed
+
+boto3_mocking.clients.register_handler("sesv2", MockSESClient)
+
+@boto3_mocking.patching
+class TestInvitations(TestCase):
+
+    """Test the retrieval of invitations."""
+
+    def setUp(self):
+        self.domain, _ = Domain.objects.get_or_create(name="igorville.gov")
+        self.email = "mayor@igorville.gov"
+        self.invitation, _ = DomainInvitation.objects.get_or_create(
+            email=self.email, domain=self.domain
+        )
+        self.user, _ = User.objects.get_or_create(email=self.email)
+
+        # clean out the roles each time
+        UserDomainRole.objects.all().delete()
+
+    def test_user_logins(self):
+        """A new user's first_login callback retrieves their invitations."""
+        self.user.first_login()
+        self.assertTrue(UserDomainRole.objects.get(user=self.user, domain=self.domain))