feat(billing): identity resolution external account -> partner

fusion_centralize_billing/tests/test_identity.py

@@ -23,3 +23,33 @@ class TestServiceApiKey(TransactionCase):
         self.assertFalse(self.Service._match_api_key('nope-not-a-key'))
         self.service.active = False
         self.assertFalse(self.Service._match_api_key(raw))
+
+
+@tagged('post_install', '-at_install')
+class TestIdentityResolution(TransactionCase):
+
+    def setUp(self):
+        super().setUp()
+        self.service = self.env['fusion.billing.service'].sudo().create(
+            {'name': 'NexaDesk', 'code': 'nexadesk'})
+        self.Link = self.env['fusion.billing.account.link'].sudo()
+
+    def test_creates_partner_first_time(self):
+        link = self.Link._resolve_or_create_partner(
+            self.service, external_id='tenant-1', name='Acme Inc', email='ar@acme.test')
+        self.assertTrue(link.partner_id)
+        self.assertEqual(link.partner_id.name, 'Acme Inc')
+        self.assertEqual(link.external_id, 'tenant-1')
+
+    def test_idempotent_same_external_id(self):
+        a = self.Link._resolve_or_create_partner(self.service, 'tenant-1', 'Acme', 'ar@acme.test')
+        b = self.Link._resolve_or_create_partner(self.service, 'tenant-1', 'Acme Renamed', 'ar@acme.test')
+        self.assertEqual(a, b)                      # same link row
+        self.assertEqual(a.partner_id, b.partner_id)  # same partner
+
+    def test_reuses_partner_by_email_across_services(self):
+        other = self.env['fusion.billing.service'].sudo().create({'name': 'Maps', 'code': 'nexamaps'})
+        a = self.Link._resolve_or_create_partner(self.service, 'tenant-1', 'Acme', 'ar@acme.test')
+        b = self.Link._resolve_or_create_partner(other, 'client-9', 'Acme', 'ar@acme.test')
+        self.assertEqual(a.partner_id, b.partner_id)  # one unified customer
+        self.assertNotEqual(a, b)                     # but distinct link rows