Quarantine BlazorWebJsInitializersTest.InitializersRunsModernCallbacksByDefaultWhenPresent is flaky

[github-actions]

Failing Test(s)

Microsoft.AspNetCore.Components.E2ETests.ServerRenderingTests.BlazorWebJsInitializersTest.InitializersRunsModernCallbacksByDefaultWhenPresent

Symptoms

Test has failed 23 times across 11 builds in the components-e2e pipeline (definition 87) over the last 30 days.

Error message:

Assert.NotEmpty() Failure: Collection was empty
```

**Root cause:** The browser logs a "Severe" console error:
```
Failed to load module script: Expected a JavaScript-or-Wasm module but the server
responded with a MIME type of ''. Strict MIME type checking is enforced for module
scripts per HTML spec.

The test checks that initializer callbacks were invoked, but when a module script fails to load due to a MIME type issue, the callbacks are never fired, leaving the collection empty.

Failing builds

• Build 1373948 — April 10, 2026
• Multiple earlier builds spanning March–April 2026

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: 23 failures across 11 builds over the last 30 days

Most recent failing build: 1373948 — April 10, 2026

Error message

Assert.NotEmpty() Failure: Collection was empty
```

### Root cause analysis

The Selenium browser logs reveal a "Severe" console error:

```
Failed to load module script: Expected a JavaScript-or-Wasm module but the server
responded with a MIME type of '' (empty string). Strict MIME type checking is
enforced for module scripts per HTML spec.

When this happens, the JavaScript initializer module fails to load, so the initializer callbacks are never registered or invoked. The test then checks for DOM elements that should have been added by those callbacks — finding none, Assert.NotEmpty() fails.

This is an intermittent server-side infrastructure issue (incorrect MIME type served for .js module files), not a code correctness bug in the component being tested. The test is valid but cannot reliably run until the MIME type serving issue is resolved or becomes consistently reproducible.

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 · ◷