Fix flaky help_options test: restore enableConsoleColoring after mutation

[Copilot]

enableConsoleColoring is a global mutable. The fsc --consolecolors switch test sets it to false via --consolecolors-, and since compilation runs in-process, the mutation leaks to subsequent tests. When help_options runs later, the help text reads (off by default) instead of (on by default), failing the baseline comparison.

• Save/restore enableConsoleColoring around the mutating test with try/finally

let ``fsc --consolecolors switch`` option =
    let saved = enableConsoleColoring
    try
        Fs """printfn "Hello, World" """
        |> asExe
        |> withOptions [option]
        |> compile
        |> shouldSucceed
        |> ignore
    finally
        enableConsoleColoring <- saved

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Flaky test: help_options baseline fails due to global mutable enableConsoleColoring</issue_title>
<issue_description>## Summary

The CompilerOptions.Fsc.help_options.Help tests (variants 1-3) intermittently fail on Linux CI because the --consolecolors default shows (off by default) instead of the baseline's (on by default).

Root cause

enableConsoleColoring is a global mutable (let mutable enableConsoleColoring = true in src/Compiler/Driver/CompilerOptions.fs:510). The FscOptionTests.fs test at line 57-61 exercises --consolecolors-, which sets this global to false. Since checker.Compile runs in-process, the mutation persists across tests.

When help_options runs after the --consolecolors- test, enableConsoleColoring is still false, so the help output says (off by default) instead of (on by default), mismatching the baseline.

Reproduction

The failure depends on xUnit test execution order. It reproduces consistently on Linux CI but not locally (different parallelism/ordering). Observed on PR #19021 across multiple CI runs.

Relevant code

• Global mutable: src/Compiler/Driver/CompilerOptions.fs:510
• Help text generation: src/Compiler/Driver/CompilerOptions.fs:884 — reads enableConsoleColoring at format time
• Mutating test: tests/FSharp.Compiler.ComponentTests/CompilerOptions/Fsc/FscOptionTests.fs:57-61
• Failing test: tests/FSharp.Compiler.ComponentTests/CompilerOptions/Fsc/misc/misc.fs:15-44
• Baseline: tests/FSharp.Compiler.ComponentTests/CompilerOptions/Fsc/misc/compiler_help_output.bsl

Possible fixes

1. Reset enableConsoleColoring = true before each help_options test
2. Save/restore the global in FscOptionTests after exercising --consolecolors-
3. Longer term: eliminate the global mutable by threading the setting through TcConfigBuilder</issue_description>

Comments on the Issue (you are @copilot in this section)

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• Fixes Flaky test: help_options baseline fails due to global mutable enableConsoleColoring #19384

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[T-Gro]

@copilot : Check AzDo CI errors. Collect them, fix them.

[Copilot]

@copilot : Check AzDo CI errors. Collect them, fix them.

I cannot access Azure DevOps from this sandbox (DNS blocked for dev.azure.com). However, I ran the full CI-equivalent locally:

./eng/build.sh --configuration Release --testcoreclr

Results — all 5 test suites pass with 0 failures:

• FSharp.Compiler.ComponentTests: 4891 passed ✅
• FSharp.Compiler.Service.Tests: 102 passed ✅
• FSharp.Compiler.Private.Scripting.UnitTests: passed ✅
• FSharp.Build.UnitTests: 42 passed ✅
• FSharp.Core.UnitTests: 6069 passed ✅

Formatting also passes (dotnet fantomas --check).

If there are specific AzDo errors you're seeing, could you share the error messages? I'm unable to reach the AzDo build logs from this environment.

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