feat(migration): enforce that in-person flows have an eligibility policy

data migration handles removing "in_person" from flows that do not have
a policy in the `in_person.context.eligibility_index` dict.

`EnrollmentFlow.clean` handles enforcing this rule going forward when
creating or editing flows.

benefits/core/migrations/0036_in_person_enrollmentflows.py

@@ -0,0 +1,23 @@
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("core", "0035_enrollmentflow_system_name_choices"),
+    ]
+
+    def migrate_in_person_flows(apps, schema_editor):
+        EnrollmentFlow = apps.get_model("core", "EnrollmentFlow")
+        for flow in EnrollmentFlow.objects.all():
+            in_person = "in_person"  # value of EnrollmentMethods.IN_PERSON as of this migration
+            if in_person in flow.supported_enrollment_methods:
+                if flow.system_name not in [
+                    "senior",
+                    "medicare",
+                    "courtesy_card",
+                ]:  # the keys in `in_person.context.eligibility_index` as of this migration
+                    flow.supported_enrollment_methods.remove(in_person)
+                    flow.save()
+
+    operations = [migrations.RunPython(migrate_in_person_flows)]

benefits/core/models/enrollment.py

@@ -263,7 +263,7 @@ def in_person_eligibility_context(self):
         return in_person_context.eligibility_index[self.system_name].dict()
 
     def clean(self):
-        template_errors = []
+        errors = []
 
         if self.transit_agency:
             templates = [
@@ -281,10 +281,19 @@ def clean(self):
             # so just create directly for a missing template
             for t in templates:
                 if not template_path(t):
-                    template_errors.append(ValidationError(f"Template not found: {t}"))
+                    errors.append(ValidationError(f"Template not found: {t}"))
 
-        if template_errors:
-            raise ValidationError(template_errors)
+            if EnrollmentMethods.IN_PERSON in self.supported_enrollment_methods:
+                try:
+                    in_person_eligibility_context = self.in_person_eligibility_context
+                except KeyError:
+                    in_person_eligibility_context = None
+
+                if not in_person_eligibility_context:
+                    errors.append(ValidationError(f"In-person eligibility context not found for: {self.system_name}"))
+
+        if errors:
+            raise ValidationError(errors)
 
     def eligibility_form_instance(self, *args, **kwargs):
         """Return an instance of this flow's EligibilityForm, or None."""

tests/pytest/core/models/test_enrollment.py

@@ -255,6 +255,16 @@ def test_EnrollmentFlow_clean_templates(model_EnrollmentFlow_with_scope_and_clai
         model_EnrollmentFlow_with_scope_and_claim.clean()
 
 
+@pytest.mark.django_db
+def test_EnrollmentFlow_clean_in_person_eligibility_context_not_found(model_EnrollmentFlow):
+    model_EnrollmentFlow.system_name = "nonexistent_system_name"
+
+    with pytest.raises(
+        ValidationError, match=f"In-person eligibility context not found for: {model_EnrollmentFlow.system_name}"
+    ):
+        model_EnrollmentFlow.clean()
+
+
 @pytest.mark.django_db
 def test_EnrollmentEvent_create(model_TransitAgency, model_EnrollmentFlow):
     ts = timezone.now()