Quarantine ServerVirtualizationTest.DynamicContent_PrependItemsWhileScrolledToMiddle_VisibleItemsStayInPlace is flaky

[github-actions]

Failing Test(s)

Microsoft.AspNetCore.Components.E2ETest.ServerExecutionTests.ServerVirtualizationTest.DynamicContent_PrependItemsWhileScrolledToMiddle_VisibleItemsStayInPlace

Symptoms

Test has failed 4 times in the components-e2e pipeline (definition 87) over the last 30 days. The base VirtualizationTest variant (WASM/static) passes consistently; only the server-execution variant is flaky.

Error message:

Assert.True() Failure

The test prepends items to a virtualized list while scrolled to the middle and asserts the visible items stay in place. In server-side Blazor mode, the asynchronous update timing causes the assertion to see a stale position before the DOM has converged.

Failing builds

• Build 1363611
• Build 1365779
• Build 1370364
• Build 1370467

Note

🔒 Integrity filter blocked 22 items

The following items were blocked because they don't meet the GitHub integrity level.

• #66271 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66251 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66239 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66228 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66172 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66168 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66159 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66137 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66135 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66092 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66084 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66061 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66060 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #65893 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #65891 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #65880 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• ... and 6 more items

To allow these resources, lower min-integrity in your GitHub frontmatter:

tools:
  github:
    min-integrity: approved  # merged | approved | unapproved | none

Generated by Daily Test Quarantine Management · ● 11.7M · ◷

[github-actions]

Investigation

Pipeline: components-e2e (definition 87), refs/heads/main

Failure count: 4 failures across 4 builds over the last 30 days

Failing builds:

• 1363611
• 1365779
• 1370364
• 1370467

Error message

Assert.True() Failure

Root cause analysis

The base VirtualizationTest.DynamicContent_PrependItemsWhileScrolledToMiddle_VisibleItemsStayInPlace passes consistently (71p/0f over 71 builds). Only the server-execution variant (ServerVirtualizationTest) fails.

The test:

1. Scrolls a virtualized list to the middle
2. Prepends items to the data source
3. Asserts the previously-visible items remain at the same visual position

In server-side Blazor, the component update is asynchronous. The assertion fires before the server has finished diffing and applying the DOM update with the prepend offset correction, causing the Assert.True() to see stale item positions.

This is a known category of server-side timing flakiness in Virtualize E2E tests.

Note

🔒 Integrity filter blocked 22 items

The following items were blocked because they don't meet the GitHub integrity level.

• #66271 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66251 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66239 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66228 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66172 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66168 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66159 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66137 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66135 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66092 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66084 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66061 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #66060 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #65893 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #65891 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #65880 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• ... and 6 more items

To allow these resources, lower min-integrity in your GitHub frontmatter:

tools:
  github:
    min-integrity: approved  # merged | approved | unapproved | none

Generated by Daily Test Quarantine Management · ● 11.7M · ◷

[ilonatommy]

It should be fixed by #66262. I don't want to complicate the anchoring PR with unquarantining, leaving here a note that it should be done separately after merge.