stripe: Delete fixed price plan offer if customer on comp access plan.

Updates delete_fixed_price_plan to use the same structure as
configure_fixed_price_plan. If there is a customer plan and it's
billable, then we delete the configured CustomerPlan object. If
there is no customer plan or it's a complimentary access plan, we
delete the configured CustomerPlanOffer object.

corporate/lib/stripe.py

@@ -1561,13 +1561,7 @@ class BillingSession(ABC):
         customer = self.get_customer()
         assert customer is not None
         current_plan = get_current_plan_by_customer(customer)
-        if current_plan is None:
+        if current_plan is not None and self.check_plan_tier_is_billable(current_plan.tier):
-            fixed_price_offer = CustomerPlanOffer.objects.filter(
-                customer=customer, status=CustomerPlanOffer.CONFIGURED
-            ).first()
-            assert fixed_price_offer is not None
-            fixed_price_offer.delete()
-            return "Fixed-price plan offer deleted"
             fixed_price_next_plan = CustomerPlan.objects.filter(
                 customer=customer,
                 status=CustomerPlan.NEVER_STARTED,
@@ -1576,6 +1570,12 @@ class BillingSession(ABC):
             assert fixed_price_next_plan is not None
             fixed_price_next_plan.delete()
             return "Fixed-price scheduled plan deleted"
+        fixed_price_offer = CustomerPlanOffer.objects.filter(
+            customer=customer, status=CustomerPlanOffer.CONFIGURED
+        ).first()
+        assert fixed_price_offer is not None
+        fixed_price_offer.delete()
+        return "Fixed-price plan offer deleted"
 
     def update_customer_sponsorship_status(self, sponsorship_pending: bool) -> str:
         customer = self.get_customer()

corporate/tests/test_stripe.py

@@ -7747,8 +7747,7 @@ class TestRemoteRealmBillingFlow(StripeTestCase, RemoteRealmBillingTestCase):
             self.assert_in_response(substring, response)
 
     @responses.activate
-    @mock_stripe()
+    def test_delete_configured_fixed_price_plan_offer_no_active_plan(self) -> None:
-    def test_delete_configured_fixed_price_plan_offer(self, *mocks: Mock) -> None:
         self.login("iago")
 
         self.add_mock_response()
@@ -7803,6 +7802,90 @@ class TestRemoteRealmBillingFlow(StripeTestCase, RemoteRealmBillingTestCase):
             ["Configure fixed price plan", "Annual amount in dollars"], result
         )
 
+    @responses.activate
+    def test_delete_configured_fixed_price_plan_offer_on_complimentary_access_plan(self) -> None:
+        self.login("iago")
+
+        self.add_mock_response()
+        with time_machine.travel(self.now, tick=False):
+            send_server_data_to_push_bouncer(consider_usage_statistics=False)
+
+        self.assertFalse(CustomerPlanOffer.objects.exists())
+        annual_fixed_price = 1200
+
+        # Configure complimentary access plan
+        complimentary_access_plan_end = self.next_year.strftime("%Y-%m-%d")
+        billing_session = RemoteRealmBillingSession(remote_realm=self.remote_realm)
+        support_request = SupportViewRequest(
+            support_type=SupportType.configure_complimentary_access_plan,
+            plan_end_date=complimentary_access_plan_end,
+        )
+
+        with time_machine.travel(self.now, tick=False):
+            success_message = billing_session.process_support_view_request(support_request)
+        self.assertEqual(
+            success_message,
+            f"Complimentary access plan for Zulip Dev configured to end on {complimentary_access_plan_end}.",
+        )
+
+        # Configure required_plan_tier and fixed_price.
+        result = self.client_post(
+            "/activity/remote/support",
+            {
+                "remote_realm_id": f"{self.remote_realm.id}",
+                "required_plan_tier": CustomerPlan.TIER_SELF_HOSTED_BASIC,
+            },
+        )
+        self.assert_in_success_response(
+            ["Required plan tier for Zulip Dev set to Zulip Basic."], result
+        )
+
+        result = self.client_post(
+            "/activity/remote/support",
+            {"remote_realm_id": f"{self.remote_realm.id}", "fixed_price": annual_fixed_price},
+        )
+        self.assert_in_success_response(
+            ["Customer can now buy a fixed price Zulip Basic plan."], result
+        )
+        fixed_price_plan_offer = CustomerPlanOffer.objects.filter(
+            status=CustomerPlanOffer.CONFIGURED
+        ).first()
+        assert fixed_price_plan_offer is not None
+        self.assertEqual(fixed_price_plan_offer.tier, CustomerPlanOffer.TIER_SELF_HOSTED_BASIC)
+        self.assertEqual(fixed_price_plan_offer.fixed_price, annual_fixed_price * 100)
+        self.assertEqual(fixed_price_plan_offer.get_plan_status_as_text(), "Configured")
+
+        result = self.client_get("/activity/remote/support", {"q": "example.com"})
+        self.assert_in_success_response(
+            [
+                "Next plan information:",
+                "Zulip Basic",
+                "Configured",
+                "Plan has a fixed price.",
+                "Zulip Basic (complimentary)",
+            ],
+            result,
+        )
+
+        # Delete configured fixed price plan.
+        billing_session = RemoteRealmBillingSession(remote_realm=self.remote_realm)
+        support_request = SupportViewRequest(
+            support_type=SupportType.delete_fixed_price_next_plan,
+        )
+        success_message = billing_session.process_support_view_request(support_request)
+        self.assertEqual(success_message, "Fixed-price plan offer deleted")
+        result = self.client_get("/activity/remote/support", {"q": "example.com"})
+        self.assert_not_in_success_response(["Next plan information:"], result)
+        self.assert_in_success_response(
+            [
+                "Configure fixed price plan",
+                "Annual amount in dollars",
+                "Zulip Basic (complimentary)",
+            ],
+            result,
+        )
+        self.assertFalse(CustomerPlanOffer.objects.exists())
+
     @responses.activate
     @mock_stripe()
     def test_upgrade_user_to_fixed_price_plan_pay_by_invoice(self, *mocks: Mock) -> None: