Catch the exception if the visit count rule doesn't have a page

src/wagtail_personalisation/rules.py

@@ -6,6 +6,7 @@ from importlib import import_module
 
 from django.apps import apps
 from django.conf import settings
+from django.core.exceptions import ObjectDoesNotExist
 from django.contrib.sessions.models import Session
 from django.db import models
 from django.template.defaultfilters import slugify
@@ -239,6 +240,12 @@ class VisitCountRule(AbstractBaseRule):
         from wagtail_personalisation.adapters import (
             get_segment_adapter, SessionSegmentsAdapter, SEGMENT_ADAPTER_CLASS)
 
+        # Django formsets don't honour 'required' fields so check rule is valid
+        try:
+            self.counted_page
+        except ObjectDoesNotExist:
+            return False
+
         if user:
             # Create a fake request so we can use the adapter
             request = RequestFactory().get('/')

tests/unit/test_rules_visitcount.py

@@ -2,6 +2,7 @@ import pytest
 
 from tests.factories.rule import VisitCountRuleFactory
 from tests.factories.segment import SegmentFactory
+from wagtail_personalisation.rules import VisitCountRule
 
 
 @pytest.mark.django_db
@@ -25,6 +26,12 @@ def test_visit_count(site, client):
     assert visit_count[1]['count'] == 1
 
 
+@pytest.mark.django_db
+def test_call_test_user_on_invalid_rule_fails(site, user, mocker):
+    rule = VisitCountRule()
+    assert not (rule.test_user(None, user))
+
+
 @pytest.mark.django_db
 def test_visit_count_call_test_user_with_user(site, client, user):
     segment = SegmentFactory(name='VisitCount')