add an imsm integration test

examples/answers-imsm.yaml

@@ -0,0 +1,35 @@
+#machine-config: examples/imsm.json
+Welcome:
+  lang: en_US
+Refresh:
+  update: no
+Keyboard:
+  layout: us
+Network:
+  accept-default: yes
+Proxy:
+  proxy: ""
+Mirror:
+  mirror: "http://us.archive.ubuntu.com"
+Filesystem:
+  guided: yes
+  guided-label: "md126"
+Identity:
+  realname: Ubuntu
+  username: ubuntu
+  hostname: ubuntu-server
+  # ubuntu
+  password: '$6$wdAcoXrU039hKYPd$508Qvbe7ObUnxoj15DRCkzC3qO7edjH0VV7BPNRDYK4QR8ofJaEEF2heacn0QgD.f8pO8SNp83XNdWG6tocBM1'
+SSH:
+  install_server: true
+  pwauth: false
+  authorized_keys:
+    - |
+      ssh-rsa AAAAAAAAAAAAAAAAAAAAAAAAA # ssh-import-id lp:subiquity
+SnapList:
+  snaps:
+    hello:
+      channel: stable
+      is_classic: false
+InstallProgress:
+  reboot: yes

subiquity/client/controllers/filesystem.py

@@ -85,7 +85,12 @@ class FilesystemController(SubiquityTuiController, FilesystemManipulator):
             await asyncio.sleep(0.1)
 
         if self.answers['guided']:
+            if 'guided-index' in self.answers:
                 disk = self.ui.body.form.disks[self.answers['guided-index']]
+            elif 'guided-label' in self.answers:
+                label = self.answers['guided-label']
+                [disk] = [d for d in self.ui.body.form.disks
+                          if d.label == label]
             method = self.answers.get('guided-method')
             self.ui.body.form.guided_choice.value = {
                 'disk': disk,