fix(computes): a disk is offered the host's disk buses

The bus list of a disk on the VM create page came from the host's disk
device types: choosing "disk" for an added image offered cdrom, disk and
lun as its buses. The disk branch of get_disk_buses now returns the
host's disk bus types, the list the page starts each disk with.

computes/tests/test_views.py

@@ -1,4 +1,6 @@
+import json
 import os
+from unittest.mock import patch
 from django.core.exceptions import ObjectDoesNotExist
 from django.shortcuts import reverse
 from django.test import RequestFactory, TestCase, TransactionTestCase
@@ -177,6 +179,13 @@ class ComputesTestCase(TestCase):
         )
         self.assertEqual(response.status_code, 200)
 
+    def test_a_disk_is_offered_the_hosts_disk_buses(self):
+        with patch("computes.views.wvmConnect") as conn:
+            conn.return_value.get_disk_device_types.return_value = ["disk", "cdrom", "lun"]
+            conn.return_value.get_disk_bus_types.return_value = ["virtio", "sata", "scsi"]
+            response = self.client.get(reverse("buses", args=[self.compute.id, "x86_64", "q35", "disk"]))
+        self.assertEqual(json.loads(response.content), {"bus": ["sata", "scsi", "virtio"]})
+
     def test_dom_capabilities(self):
         self._require_live_compute()
         response = self.client.get(

computes/views.py

@@ -215,7 +215,7 @@ class ComputeManager:
 
             if disk in disk_device_types:
                 if disk == "disk":
-                    data["bus"] = sorted(disk_device_types)
+                    data["bus"] = sorted(self.conn.get_disk_bus_types(arch, machine))
                 elif disk == "cdrom":
                     data["bus"] = ["ide", "sata", "scsi"]
                 elif disk == "floppy":