def test_cluster_division_separates_cluster_with_unrelated_items(scotland, alba, england, goat):
cluster_scotland = Cluster()
cluster_scotland.save()
cluster_england_and_goat = Cluster()
cluster_england_and_goat.save()
scotland.cluster = cluster_scotland
scotland.save()
alba.cluster = cluster_scotland
alba.save()
england.cluster = cluster_england_and_goat
england.save()
goat.cluster = cluster_england_and_goat
goat.save()
Cluster.clear_empty()
assert Cluster.objects.count() == 2
Cluster.divide()
# Django won't notice the clusters changing unless we re-read fields
scotland.refresh_from_db()
england.refresh_from_db()
goat.refresh_from_db()
# We expect one cluster to divide, so our original 2 are now 3
assert Cluster.objects.count() == 3
# Scotland cluster untouched as it has two identical items
assert len(cluster_scotland) == 2
# England and Goat should be in their own clusters as they are unrelated
assert england.cluster != goat.cluster
