Quarantine VirtualizationTest.CanRenderHtmlTable and CanElevateEffectiveMaxItemCount_WhenOverscanExceedsMax failing intermittently

[github-actions]

Failing Test(s)

• Microsoft.AspNetCore.Components.E2ETest.ServerExecutionTests.ServerVirtualizationTest.CanRenderHtmlTable
• Microsoft.AspNetCore.Components.E2ETest.ServerExecutionTests.ServerVirtualizationTest.CanElevateEffectiveMaxItemCount_WhenOverscanExceedsMax

Error Message

Assert.Contains() Failure: Sub-string not found
String:   "height: 30px; flex-shrink: 0; display: ta..."
Not found: "height: 0px; flex-shrink: 0;"

Stacktrace

Details

Assert.Contains() Failure: Sub-string not found
String:   "height: 30px; flex-shrink: 0; display: table; width: 100%;"
Not found: "height: 0px; flex-shrink: 0;"
   at Microsoft.AspNetCore.Components.E2ETest.Tests.VirtualizationTest.CanRenderHtmlTable()

Logs

Details

See build logs for detailed output. Test is checking CSS spacer height values which can vary due to timing in E2E tests.

Build

https://dev.azure.com/dnceng-public/public/_build/results?buildId=1341040

Generated by Daily Test Quarantine Management · ◷

[github-actions]

Investigation

These E2E Blazor Virtualization tests intermittently fail due to CSS spacer height values not matching expected values in the virtualized list component.

Root cause: The tests verify that spacer elements in a virtualized list start with height: 0px; flex-shrink: 0; but intermittently the spacer height is 30px instead of 0px. This suggests a race condition between component rendering and test assertion — the test is reading the DOM state before the virtualization component has finished its initial layout calculation and reset the spacer height.

Specifically in CanRenderHtmlTable, the test expects the initial spacer style to be height: 0px; flex-shrink: 0; but sees height: 30px; flex-shrink: 0;, indicating the spacer was measured at a non-zero height before the component settled.

This is a timing-sensitive E2E test issue running against a browser. The fix would require either:

1. Adding a wait condition for the component to complete its initial render
2. Using a polling assertion instead of a point-in-time assertion

Quarantine PR: The tests are being quarantined to unblock CI until the timing issue can be addressed.

Generated by Daily Test Quarantine Management · ◷

[github-actions]

All tests quarantined under this issue have been passing with a 100% pass rate for 30+ days in the quarantined-tests pipeline (definition 84). The [QuarantinedTest] attribute has been removed via the unquarantine PR. Closing this issue.