Merge ~ack/maas:1939340-3.0 into maas:3.0

[Alberto Donato]

LP:1939340 handle "interfaces" field for reported USB devices being null

[Alberto Donato (ack)]

review: Approve

diff --git a/src/metadataserver/builtin_scripts/hooks.py b/src/metadataserver/builtin_scripts/hooks.py
index fd52cdd..9ea7b89 100644
--- a/src/metadataserver/builtin_scripts/hooks.py
+++ b/src/metadataserver/builtin_scripts/hooks.py
@@ -465,13 +465,15 @@ def _process_usb_devices(add_func, data):
             device["device_address"],
         )
         key = (device["vendor_id"], device["product_id"], usb_address)
+        # the "interfaces" field can be present but None
+        interfaces = device.get("interfaces") or []
         # USB devices can have different drivers for each
         # functionality. e.g a webcam has a video and audio driver.
         commissioning_driver = ", ".join(
             set(
                 [
                     interface["driver"]
-                    for interface in device.get("interfaces", [])
+                    for interface in interfaces
                     if "driver" in interface
                 ]
             )
diff --git a/src/metadataserver/builtin_scripts/tests/test_hooks.py b/src/metadataserver/builtin_scripts/tests/test_hooks.py
index 4e36ffa..f7563fc 100644
--- a/src/metadataserver/builtin_scripts/tests/test_hooks.py
+++ b/src/metadataserver/builtin_scripts/tests/test_hooks.py
@@ -1556,6 +1556,29 @@ class TestProcessLXDResults(MAASServerTestCase):
             pcie_node_device.pci_address, pcie_device["pci_address"]
         )
 
+    def test_usb_device_null_interfaces(self):
+        node = factory.make_Node()
+        lxd_output = make_lxd_output()
+        usb_device = make_lxd_usb_device()
+        usb_device["interfaces"] = None
+        lxd_output["resources"]["usb"] = {
+            "devices": [usb_device],
+            "total": 1,
+        }
+        process_lxd_results(node, json.dumps(lxd_output).encode(), 0)
+        usb_node_device = node.node_devices.get(bus=NODE_DEVICE_BUS.USB)
+        self.assertEqual(usb_node_device.hardware_type, HARDWARE_TYPE.NODE)
+        self.assertEqual(usb_node_device.vendor_id, usb_device["vendor_id"])
+        self.assertEqual(usb_node_device.product_id, usb_device["product_id"])
+        self.assertEqual(usb_node_device.vendor_name, usb_device["vendor"])
+        self.assertEqual(usb_node_device.product_name, usb_device["product"])
+        self.assertEqual(usb_node_device.bus_number, usb_device["bus_address"])
+        self.assertEqual(usb_node_device.commissioning_driver, "")
+        self.assertEqual(
+            usb_node_device.device_number, usb_device["device_address"]
+        )
+        self.assertIsNone(usb_node_device.pci_address)
+
     def test_updates_node_device(self):
         node = factory.make_Node()
         pcie_device = factory.make_NodeDevice(