Replace fixed-duration sleeps in tests with deterministic waits

[agners]

Proposed change

Several tests use await asyncio.sleep(...) to "wait for the handler to run" after firing an event or unblocking a task. The fixed duration is real wall-clock time and is also flaky if the handler chain happens to need slightly more time on a busy CI runner.

Replace each site with a wait targeted at what is actually being scheduled:

• Bus.fire_event returns the listener tasks since Migrate images from dockerpy to aiodocker #6252; capture and await asyncio.gather(*tasks) instead of sleeping. Touches test_bus.py, test_home_assistant_watchdog.py, test_plugin_base.py, docker/test_addon.py, and resolution/fixup/test_store_execute_reload.py.
• _fire_test_event in addons/test_addon.py becomes async def and gathers internally, so its 17 call sites collapse to a single await _fire_test_event(...).
• The two test_store_execute_reload.py sites that used the private _update_connectivity() helper are reworked to set the cached connectivity flag directly and fire the event themselves so they can gather the listener tasks the same way.
• For fire-and-forget sys_create_task jobs whose only handle is the coroutine name, the coresys test fixture now wraps coresys.create_task to record every spawned task into a per-test list. The new tests.common.wait_for_task_by_name helper looks tasks up there (rather than from asyncio.all_tasks(), which only includes pending tasks) so it works even if the task has already finished by the time the test asserts. Used for BackupManager.reload (3 sites in api/test_backups.py), the scheduled connectivity check in test_supervisor.py, and the four DNS-debounce timer callbacks in plugins/test_dns.py. Raises LookupError if the named task was never scheduled — that is a test bug, the call site expects the work to have happened.
• The two sleep(1) post-pull drains in docker/test_interface.py collapse to sleep(0) (handler tasks are already gathered inside pull_image), saving ~2s.
• The sleep(0.01) waits inside container_events() task bodies (test_addons.py, test_store.py, test_manager.py) are just one-yield-to-the-parent and become sleep(0).

Switching to gather exposes a few latent test mocks that were silently swallowing TypeErrors as background-task failures: CGroup.add_devices_allowed is async def but was patched as a plain MagicMock in docker/test_addon.py (now new_callable=AsyncMock), and the watchdog does await (await self.start()) / await (await self.restart()) because App.start / App.restart return asyncio.Task — the mocks in addons/test_addon.py (test_app_watchdog, test_watchdog_on_stop, test_watchdog_during_attach) needed AsyncMock(return_value=<settled future>) to mirror that shape rather than a plain MagicMock.

Tests that wait on real D-Bus signal round-trips through the dbus-daemon subprocess (test_data_disk.py, dbus/udisks2/test_manager.py, mounts/test_mount.py, test_core.py, host/test_firewall.py) need real wall-clock time for the in-flight stop/start unit calls to settle and the property-change subscription to be in place before the test emits the signal — they keep their existing sleep(0.1). Same for tests where the sleep itself is the test point (job throttle, scheduler timing, freeze/thaw timeout).

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (which adds functionality to the supervisor)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:
• Link to cli pull request:
• Link to client library pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Ruff (ruff format supervisor tests)
• Tests have been added to verify that the new code works.

If API endpoints or add-on configuration are added/changed:

• Documentation added/updated for developers.home-assistant.io
• CLI updated (if necessary)
• Client library updated (if necessary)

[agners]

I've run this on Python 3.14.2 (just since it seems to have different behavior when it comes to asyncio/scheduling as we see in Core) and a couple of times in CI here, the tests all seem stable with this change.

[Copilot]

Pull request overview

This PR improves test determinism by replacing fixed-duration asyncio.sleep(...) calls with helpers that yield control to the event loop or await specific background tasks, reducing wall-clock delays and flakiness on busy CI runners.

Changes:

• Added yield_to_event_loop() and wait_for_task_by_name() helpers in tests/common.py to replace fixed sleeps with deterministic waits.
• Updated multiple tests to use yield_to_event_loop() after in-process events, and replaced small non-deterministic delays with asyncio.sleep(0) where a single yield is sufficient.
• Updated backups API tests to await the specific BackupManager.reload background task rather than sleeping.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/common.py	Adds new async waiting helpers intended to replace fixed-duration sleeps in tests.
tests/resolution/fixup/test_store_execute_reload.py	Replaces sleep(0.1) with yield_to_event_loop() after connectivity/event triggers.
tests/plugins/test_dns.py	Uses yield_to_event_loop() to wait for notify_locals_changed() async effects.
tests/host/test_firewall.py	Uses yield_to_event_loop() after starting apply_gateway_firewall_rules() task.
tests/homeassistant/test_home_assistant_watchdog.py	Uses yield_to_event_loop() after firing container state change events.
tests/docker/test_interface.py	Replaces sleep(1) with sleep(0) before asserting captured progress events.
tests/docker/test_addon.py	Replaces sleep(0.01) with sleep(0) after firing hardware events.
tests/backups/test_manager.py	Replaces sleep(0.01) with sleep(0) in simulated container events coroutine.
tests/api/test_store.py	Replaces sleep(0.01) with sleep(0) in simulated container events coroutine.
tests/api/test_backups.py	Uses wait_for_task_by_name() to await reload tasks spawned by API calls.
tests/api/test_addons.py	Replaces sleep(0.01) with sleep(0) in simulated container events coroutine.
tests/addons/test_manager.py	Replaces sleep(0.01) with sleep(0) in startup/uninstall wait test.
tests/addons/test_addon.py	Replaces small sleeps with yield_to_event_loop() around container state events.

[agners]

Split in two PRs for easier reviewing: #6803 and #6804. Especially the second PR is debatable if it really adds value.