tests: Adds region-based scheduling integration tests

Covers the scheduler's RegionsFilter. A  matched-region transfer schedules
and completes normally, while a worker / endpoint region mismatch
causes the execution to fail scheduling (FAILED_TO_SCHEDULE -> ERROR).

coriolis/tests/integration/management/test_region.py

@@ -3,10 +3,15 @@
 
 """Integration tests for the regions APIs.
 
-Exercises region CRUD operations via the Coriolis REST API.
+Exercises region CRUD operations via the Coriolis REST API, as well as
+scheduler behavior when workers and endpoints are mapped to regions.
 """
 
+from keystoneauth1.exceptions import http as http_exc
+
+from coriolis import constants
 from coriolis.tests.integration import base
+from coriolis import utils as coriolis_utils
 
 
 class RegionTests(base.CoriolisIntegrationTestBase):
@@ -44,3 +49,75 @@ class RegionTests(base.CoriolisIntegrationTestBase):
         regions = self._client.regions.list()
         ids = [r.id for r in regions]
         self.assertNotIn(region.id, ids)
+
+
+class RegionSchedulingTests(base.ReplicaIntegrationTestBase):
+
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls._worker_service = (
+            cls._client.services.find_service_by_host_and_topic(
+                coriolis_utils.get_hostname(),
+                constants.WORKER_MAIN_MESSAGING_TOPIC))
+        cls.addClassCleanup(
+            cls._client.services.update,
+            cls._worker_service.id, {"mapped_regions": []})
+
+    def _create_region(self, name, **kwargs):
+        region = self._client.regions.create(name, **kwargs)
+        self.addCleanup(
+            self._ignoreExc(self._client.regions.delete), region.id)
+
+        return region
+
+    def test_region_scheduling(self):
+        """Covers the scheduler's RegionsFilter.
+
+        A matched-region transfer schedules and completes normally, while
+        a worker / endpoint region mismatch causes the transfer creation
+        itself to fail.
+        The scheduler needs a region-matching worker to service the endpoint
+        validation calls for the created transfer. A region mismatch surfaces
+        as an immediate BadRequest at creation time.
+        """
+        # Matched region: reuse the src / dst endpoints and transfer created in
+        # ReplicaIntegrationTestBase.setUp.
+        matched_region = self._create_region("region-matched")
+        self._client.services.update(
+            self._worker_service.id, {"mapped_regions": [matched_region.id]})
+        self._client.endpoints.update(
+            self._src_endpoint.id, {"mapped_regions": [matched_region.id]})
+        self._client.endpoints.update(
+            self._dst_endpoint.id, {"mapped_regions": [matched_region.id]})
+
+        self._execute_and_wait(self._transfer.id)
+
+        # Mismatched region: point the worker and a fresh pair of
+        # endpoints at different regions, and assert transfer creation
+        # itself is rejected.
+        worker_region = self._create_region("region-worker")
+        endpoint_region = self._create_region("region-endpoint")
+
+        self._client.services.update(
+            self._worker_service.id, {"mapped_regions": [worker_region.id]})
+
+        src_endpoint = self._create_endpoint(
+            name="region-mismatch-src",
+            endpoint_type=self._exp_platform,
+            connection_info=self._exp_conn_info,
+            regions=[endpoint_region.id],
+        )
+        dst_endpoint = self._create_endpoint(
+            name="region-mismatch-dst",
+            endpoint_type=self._imp_platform,
+            connection_info=self._imp_conn_info,
+            regions=[endpoint_region.id],
+        )
+
+        self.assertRaises(
+            http_exc.BadRequest,
+            self._create_transfer,
+            src_endpoint.id, dst_endpoint.id,
+            ["region-mismatch-instance"],
+        )