[Flaky Test] Microsoft.Build.UnitTests.CodeTaskFactoryTests.BuildTaskSimpleCodeFactory

**Flaky-test key** (automated de-duplication — do not edit):
```text
flaky-test-id: Microsoft.Build.UnitTests.CodeTaskFactoryTests.BuildTaskSimpleCodeFactory
```

## Evidence

Multiple CodeTaskFactory tests are failing together on Windows net472 CI runs, suggesting a shared infrastructure issue (compiler/sandbox availability).

- **Distinct sources:** 3 (0 PRs + 3 rolling builds)
- **Rolling builds:** [1514373](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1514373), [1517682](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1517682), [1527742](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1527742)
- **Legs:** FullOnWindows Release
- **TFMs:** net472
- **Assembly:** Microsoft.Build.Tasks.UnitTests
- **First seen:** 2026-07-17 | **Last seen:** 2026-07-27

**Also affected (same error hash, same builds):** `BuildTaskSimpleCodeFactory_RedirectFrom4`, `BuildTaskSimpleCodeFactory_RedirectFrom12`, `BuildTaskSimpleCodeFactory_NoAssemblyNameRedirect`, `BuildTaskSimpleCodeFactoryTestExtraUsing`, `BuildTaskDateCodeFactory`, `EmbedsGeneratedFromSourceFileInBinlog`

## Sample error

```
Assert.True() Failure
Expected: True
Actual: False
```

## Fully-qualified test name

`Microsoft.Build.UnitTests.CodeTaskFactoryTests.BuildTaskSimpleCodeFactory`

Source: `src/Tasks.UnitTests/CodeTaskFactoryTests.cs`

## Next steps

This test (and related CodeTaskFactory tests) will be quarantined via `[ActiveIssue("https://github.com/dotnet/msbuild/issues/")]` (from `Microsoft.DotNet.XUnitV3Extensions`, namespace `Xunit`) until the underlying nondeterminism is fixed.

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> Generated by [Flaky Test Triage](https://github.com/dotnet/msbuild/actions/runs/30451703648) · sonnet46 · 150.7 AIC · ⌖ 5.46 AIC · ⊞ 14.7K · [◷](https://github.com/search?q=repo%3Adotnet%2Fmsbuild+is%3Aissue+%22gh-aw-workflow-call-id%3A+dotnet%2Fmsbuild%2Fflaky-test-detector.agent%22&type=issues)

Start with src/Tasks.UnitTests/CodeTaskFactoryTests.cs and reproduce Microsoft.Build.UnitTests.CodeTaskFactoryTests.BuildTaskSimpleCodeFactory on the FullOnWindows Release net472 leg. Compare the related CodeTaskFactory failures and investigate the shared compiler or sandbox availability indicated by the CI evidence. Done means the nondeterministic failures are fixed and the tests pass without quarantine.

Written by the indexing model from the issue text.