Fix coordinator data mutation in YouTube diagnostics by TomFilsell · Pull Request #170183 · home-assistant/core

TomFilsell · 2026-05-09T10:39:25Z

Proposed change

The async_get_config_entry_diagnostics function was mutating the
coordinator's live data on every diagnostics fetch.

The previous code called .pop(ATTR_DESCRIPTION) directly on
channel_data, which is a reference into coordinator.data — not a
copy. This permanently removed description from ATTR_LATEST_VIDEO
for the lifetime of the config entry, meaning any code reading that
field after a diagnostics fetch would find it missing.

Additionally, when ATTR_LATEST_VIDEO is None, the previous code
called .get(ATTR_LATEST_VIDEO, {}).pop(...) on a throwaway empty
dict, silently doing nothing rather than handling the None case
explicitly.

This fix builds a shallow copy of each channel's data and constructs
a new ATTR_LATEST_VIDEO dict excluding description, leaving
coordinator data untouched.

Type of change

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

Additional information

No functional changes to the diagnostics output (description remains
correctly excluded)
Three new tests added: coordinator data immutability, description
redaction, and explicit None latest video handling
Snapshot updated to reflect the corrected output structure

Checklist

The code change is tested and works locally
Local tests pass
There is no commented out code in this PR
I have followed the development checklist
I have followed the perfect PR recommendations
The code has been formatted using Ruff
Tests have been added to verify that the new code works

home-assistant · 2026-05-09T10:39:32Z

Hey there @joostlek, mind taking a look at this pull request as it has been labeled with an integration (youtube) you are listed as a code owner for? Thanks!

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Copilot

Pull request overview

Fixes a bug in the YouTube integration diagnostics where diagnostics generation could mutate (or previously even break on) the coordinator’s live data, by ensuring diagnostics operate on copies and safely handle latest_video=None.

Changes:

Avoid mutating coordinator.data by copying per-channel data and rebuilding latest_video without description.
Add diagnostics tests to verify coordinator data immutability, description redaction, and correct handling of latest_video=None.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
`homeassistant/components/youtube/diagnostics.py`	Stops in-place mutation of coordinator data and safely redacts `latest_video.description` without altering live state.
`tests/components/youtube/test_diagnostics.py`	Adds regression tests ensuring diagnostics don’t mutate coordinator data and handle `latest_video=None` while keeping `description` out of output.

jbouwh

Please fill i the PR description.

Split the fixed code and the Config Entry typing improvements

home-assistant · 2026-05-09T16:55:42Z

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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TomFilsell · 2026-05-10T04:25:12Z

Please fill i the PR description.

Split the fixed code and the Config Entry typing improvements

No, worries. Thanks for the feedback! I've updated the PR to contain only the diagnostics mutation bug fix. coordinator.py and init.py changes have been removed. The YouTubeConfigEntry typing improvements will be submitted as a separate PR.
I've also tidied up the PR description to remove the unused template sections.

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

+    await setup_integration()
+    entry = hass.config_entries.async_entries(DOMAIN)[0]
+    coordinator = hass.data[DOMAIN][entry.entry_id][COORDINATOR]
+


+    await setup_integration()
+    entry = hass.config_entries.async_entries(DOMAIN)[0]
+    coordinator = hass.data[DOMAIN][entry.entry_id][COORDINATOR]
+


TomFilsell · 2026-05-10T04:40:01Z

Please fill i the PR description.

Split the fixed code and the Config Entry typing improvements

Hi. Take 2.

I think the Config Entry typing changes in init.py and coordinator.py are actually a prerequisite for this fix — diagnostics.py needs to access the coordinator via entry.runtime_data because the updated async_setup_entry no longer populates hass.data. Would it be acceptable to include both changes in this PR, or would you prefer I submit the typing refactor first and rebase this on top of it?

jbouwh · 2026-05-10T05:27:50Z

I'd like the fix (mutation in the test) to be as small as possible, as this gets in to the patch release. Yeah is the first one. The second one is about code quality, and adds the typing.

TomFilsell · 2026-05-10T06:49:44Z

I'd like the fix (mutation in the test) to be as small as possible, as this gets in to the patch release. Yeah is the first one. The second one is about code quality, and adds the typing.

Thank you!
I've investigated further and it looks like the old hass.data[DOMAIN][entry.entry_id][COORDINATOR] pattern is no longer compatible with the current init.py on dev, which already uses entry.runtime_data and no longer populates hass.data. Using the old pattern causes a KeyError at runtime and in tests.

Given this, I see two options for your consideration:
either 1. Include both the typing update and the bug fix together in this PR, or
2. Submit the typing refactor as a separate PR first, then rebase this fix on top of it once merged

Happy to go whichever route you prefer just let me know!

jbouwh · 2026-05-10T13:03:12Z

I just rebased (you need to do a git pull locally. And it seems the changes you want to make are invalid. May be your checkout branch was outdated.

jbouwh · 2026-05-10T13:08:15Z

I don't think the additional tests are needed. Just copy the coordinator data like:

async def async_get_config_entry_diagnostics(
    hass: HomeAssistant, entry: YouTubeConfigEntry
) -> dict[str, Any]:
    """Return diagnostics for a config entry."""
    coordinator = entry.runtime_data
    sensor_data: dict[str, Any] = {}
    for channel_id, channel_data in dict(coordinator.data).items():
        channel_data.get(ATTR_LATEST_VIDEO, {}).pop(ATTR_DESCRIPTION)
        sensor_data[channel_id] = channel_data
    return sensor_data

jbouwh · 2026-05-10T13:11:21Z

+from homeassistant.components.youtube.const import (
+    ATTR_DESCRIPTION,
+    ATTR_LATEST_VIDEO,
+    COORDINATOR,
+    DOMAIN,
+)


Suggested change

from homeassistant.components.youtube.const import (

ATTR_DESCRIPTION,

ATTR_LATEST_VIDEO,

COORDINATOR,

DOMAIN,

)

from homeassistant.components.youtube.const import DOMAIN

jbouwh · 2026-05-10T13:11:43Z

 ) -> None:
    """Test diagnostics."""
    await setup_integration()
    entry = hass.config_entries.async_entries(DOMAIN)[0]


Suggested change

entry = hass.config_entries.async_entries(DOMAIN)[0]

entry = hass.config_entries.async_entries(DOMAIN)[0]

jbouwh · 2026-05-10T13:14:21Z

+
+
+async def test_diagnostics_does_not_mutate_coordinator_data(
+    hass: HomeAssistant,
+    hass_client: ClientSessionGenerator,
+    setup_integration: ComponentSetup,
+) -> None:
+    """Test that fetching diagnostics does not mutate the coordinator's data.
+
+    Previously, diagnostics called .pop(ATTR_DESCRIPTION) directly on the
+    coordinator's data dict, permanently removing the description from the
+    live data after the first diagnostics fetch.
+    """
+    await setup_integration()
+    entry = hass.config_entries.async_entries(DOMAIN)[0]
+    coordinator = hass.data[DOMAIN][entry.entry_id][COORDINATOR]
+


Suggested change

async def test_diagnostics_does_not_mutate_coordinator_data(

hass: HomeAssistant,

hass_client: ClientSessionGenerator,

setup_integration: ComponentSetup,

) -> None:

"""Test that fetching diagnostics does not mutate the coordinator's data.

Previously, diagnostics called .pop(ATTR_DESCRIPTION) directly on the

coordinator's data dict, permanently removing the description from the

live data after the first diagnostics fetch.

"""

await setup_integration()

entry = hass.config_entries.async_entries(DOMAIN)[0]

coordinator = hass.data[DOMAIN][entry.entry_id][COORDINATOR]

jbouwh · 2026-05-10T13:14:49Z

+    descriptions_before = {
+        channel_id: channel_data[ATTR_LATEST_VIDEO][ATTR_DESCRIPTION]
+        for channel_id, channel_data in coordinator.data.items()
+        if channel_data.get(ATTR_LATEST_VIDEO) is not None
+    }
+
+    assert descriptions_before, (
+        "Test setup should include at least one channel with a latest video"
+    )
+
+    await get_diagnostics_for_config_entry(hass, hass_client, entry)
+
+    for channel_id, description in descriptions_before.items():
+        assert (
+            coordinator.data[channel_id][ATTR_LATEST_VIDEO][ATTR_DESCRIPTION]
+            == description
+        ), (
+            f"Coordinator data was mutated for channel {channel_id}: "
+            "description was removed by diagnostics fetch"
+        )
+
+


Suggested change

descriptions_before = {

channel_id: channel_data[ATTR_LATEST_VIDEO][ATTR_DESCRIPTION]

for channel_id, channel_data in coordinator.data.items()

if channel_data.get(ATTR_LATEST_VIDEO) is not None

}

assert descriptions_before, (

"Test setup should include at least one channel with a latest video"

)

await get_diagnostics_for_config_entry(hass, hass_client, entry)

for channel_id, description in descriptions_before.items():

assert (

coordinator.data[channel_id][ATTR_LATEST_VIDEO][ATTR_DESCRIPTION]

== description

), (

f"Coordinator data was mutated for channel {channel_id}: "

"description was removed by diagnostics fetch"

)

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

+    entry.runtime_data = coordinator
    await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)


TomFilsell · 2026-05-11T02:56:03Z

Closing in favour of a cleaner PR based on current upstream dev: (#170300). Thanks again @jbouwh for the guidance.

Fix coordinator data mutation in YouTube diagnostics

db62286

Copilot AI review requested due to automatic review settings May 9, 2026 10:39

TomFilsell requested a review from joostlek as a code owner May 9, 2026 10:39

home-assistant Bot added bugfix cla-signed code-quality has-tests integration: youtube small-pr PRs with less than 30 lines. labels May 9, 2026

home-assistant Bot assigned joostlek May 9, 2026

home-assistant Bot added the Quality Scale: No score label May 9, 2026

Copilot started reviewing on behalf of TomFilsell May 9, 2026 10:40 View session

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Fix coordinator data mutation in YouTube diagnostics

3d1282c

jbouwh requested changes May 9, 2026

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home-assistant Bot marked this pull request as draft May 9, 2026 16:55

Fix coordinator data mutation in YouTube diagnostics

a609bfd

Copilot AI review requested due to automatic review settings May 10, 2026 04:24

Copilot started reviewing on behalf of TomFilsell May 10, 2026 04:24 View session

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jbouwh reviewed May 10, 2026

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Fix coordinator data mutation in YouTube diagnostics

5733314

TomFilsell force-pushed the fix/youtube-diagnostics-mutation branch from 6a007e6 to 5733314 Compare May 11, 2026 01:19

Copilot AI review requested due to automatic review settings May 11, 2026 01:19

Copilot started reviewing on behalf of TomFilsell May 11, 2026 01:19 View session

Copilot AI reviewed May 11, 2026

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Comment thread homeassistant/components/youtube/__init__.py

Comment on lines +49 to 50

entry.runtime_data = coordinator

await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)

TomFilsell closed this May 11, 2026

TomFilsell mentioned this pull request May 11, 2026

Fix coordinator data mutation in YouTube diagnostics #170300

Merged

7 tasks

github-actions Bot locked and limited conversation to collaborators May 12, 2026

	entry = hass.config_entries.async_entries(DOMAIN)[0]
	entry = hass.config_entries.async_entries(DOMAIN)[0]

		entry.runtime_data = coordinator
		await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)

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TomFilsell commented May 9, 2026 •

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