Improve handling of empty command lists in Autoinstall YAML

examples/autoinstall/empty-cmdlist.yaml

@@ -0,0 +1,25 @@
+version: 1
+locale: en_GB.UTF-8
+network:
+  version: 2
+  ethernets:
+    all-eth:
+      match:
+        name: "en*"
+      dhcp6: yes
+apt:
+  mirror-selection:
+    primary:
+    - uri: http://localhost/failed
+  fallback: offline-install
+codecs:
+  install: true
+identity:
+  realname: ''
+  username: ubuntu
+  password: '$6$wdAcoXrU039hKYPd$508Qvbe7ObUnxoj15DRCkzC3qO7edjH0VV7BPNRDYK4QR8ofJaEEF2heacn0QgD.f8pO8SNp83XNdWG6tocBM1'
+  hostname: ubuntu
+early-commands:
+  # Command list purposely empty
+late-commands:
+  # Command list purposely empty

scripts/runtests.sh

@@ -232,6 +232,18 @@ LANG=C.UTF-8 timeout --foreground 60 \
     --source-catalog examples/sources/install.yaml
 validate
 
+clean
+testname=autoinstall-empty-cmdlist
+LANG=C.UTF-8 timeout --foreground 60 \
+    python3 -m subiquity.cmd.tui \
+    --dry-run \
+    --output-base "$tmpdir" \
+    --machine-config examples/machines/simple.json \
+    --autoinstall examples/autoinstall/empty-cmdlist.yaml \
+    --kernel-cmdline autoinstall \
+    --source-catalog examples/sources/install.yaml
+validate
+
 python3 -m subiquity.cmd.schema > $tmpdir/test-schema.json
 diff -u "autoinstall-schema.json" $tmpdir/test-schema.json
 

subiquity/server/controllers/cmdlist.py

@@ -66,6 +66,8 @@ def __init__(self, app):
         self.run_event = asyncio.Event()
 
     def load_autoinstall_data(self, data):
+        if data is None:
+            return
         self.cmds = [Command(args=cmd, check=self.cmd_check) for cmd in data]
 
     def env(self):