Won't store validation results in the controller.

Instead the form itself keeps track of the active async task.
The validation state is returned from the task object itself.

subiquity/client/controllers/identity.py

@@ -50,9 +50,5 @@ class IdentityController(SubiquityTuiController):
             identity_data)
         self.app.next_screen(self.endpoint.POST(identity_data))
 
-    async def _validate_username(self, username):
+    async def validate_username(self, username):
-        self.username_validation = \
+        return await self.endpoint.validate_username.GET(username)
-            await self.endpoint.validate_username.GET(username)
-
-    def validate_username(self, _, value):
-        self.app.aio_loop.create_task(self._validate_username(value))

subiquity/ui/views/identity.py

@@ -20,6 +20,7 @@ import re
 from urwid import (
     connect_signal,
     )
+from subiquitycore.async_helpers import schedule_task
 
 from subiquitycore.ui.interactive import (
     PasswordEditor,
@@ -85,9 +86,10 @@ class IdentityForm(Form):
 
     def __init__(self, controller, initial):
         self.controller = controller
+        self.validation_task = None
         super().__init__(initial=initial)
         connect_signal(self.username.widget, 'change',
-                       controller.validate_username)
+                       self.on_username_change)
 
     realname = RealnameField(_("Your name:"))
     hostname = UsernameField(
@@ -97,6 +99,23 @@ class IdentityForm(Form):
     password = PasswordField(_("Choose a password:"))
     confirm_password = PasswordField(_("Confirm your password:"))
 
+    def on_username_change(self, _, value):
+        if len(value) < 2:
+            return
+
+        if self.validation_task is not None:
+            self.validation_task.cancel()
+
+        self.validation_task = \
+            schedule_task(self.controller.validate_username(value))
+
+    def username_validation_state(self):
+        task = self.validation_task
+        if task is None or not task.done():
+            return UsernameValidation.OK
+
+        return task.result()
+
     def validate_realname(self):
         if len(self.realname.value) > REALNAME_MAXLEN:
             return _(
@@ -118,7 +137,6 @@ class IdentityForm(Form):
 
     def validate_username(self):
         username = self.username.value
-        state = self.controller.username_validation
         if len(username) < 1:
             return _("Username missing")
 
@@ -131,6 +149,7 @@ class IdentityForm(Form):
             return _(
                 "Username must match USERNAME_REGEX: " + USERNAME_REGEX)
 
+        state = self.username_validation_state()
         if state == UsernameValidation.SYSTEM_RESERVED:
             return _(
                 'The username "{username}" is reserved for use by the system.'

subiquity/ui/views/tests/test_identity.py

@@ -1,3 +1,4 @@
+import asyncio
 import unittest
 from unittest import mock
 
@@ -65,22 +66,24 @@ class IdentityViewTests(unittest.TestCase):
         view_helpers.enter_data(view.form, valid_data)
         self.assertTrue(view.form.done_btn.enabled)
 
-    def test_username_validation_system_reserved(self):
+    async def test_username_validation_system_reserved(self):
         view = self.make_view()
-        view.controller.username_validation = \
+        view.controller.validate_username.return_value = \
             UsernameValidation.SYSTEM_RESERVED
         view_helpers.enter_data(view.form, system_reserved)
+        await asyncio.wait(view.form.validation_task)
         self.assertFalse(view.form.done_btn.enabled)
 
-    def test_username_validation_in_use(self):
+    async def test_username_validation_in_use(self):
         view = self.make_view()
-        view.controller.username_validation = UsernameValidation.ALREADY_IN_USE
+        view.controller.validate_username.return_value = \
+            UsernameValidation.ALREADY_IN_USE
         view_helpers.enter_data(view.form, already_taken)
+        await asyncio.wait(view.form.validation_task)
         self.assertFalse(view.form.done_btn.enabled)
 
     def test_username_validation_too_long(self):
         view = self.make_view()
-        view.controller.username_validation = UsernameValidation.TOO_LONG
         view_helpers.enter_data(view.form, too_long)
         self.assertFalse(view.form.done_btn.enabled)