[rust] fix flaky tests

[titusfortner]

💥 What does this PR do?

• Fixes two unrelated sources of flakiness in the Selenium Manager browser tests

🔧 Implementation Notes

• browser_path_version_mismatch_test and browser_path_major_version_mismatch_test both wrote /tmp/fake-chrome-131-0-6778-264, so in parallel each could overwrite the other's fake browser mid-run; each now gets its own tempfile::tempdir(). Passes 3/3 with --runs_per_test=3.
• geckodriver has no linux-aarch64 build before 0.32.0 and every Firefox case here asks for 0.31.0 or older, so those downloads 404. They are now skipped on arm64 the same way the Chrome and Edge cases already are.

🤖 AI assistance

• No substantial AI assistance used
• AI assisted (complete below)
  • Tool(s): Claude Code (Opus 5)
  • What was generated: diagnosis, fix, and this description
  • I reviewed all AI output and can explain the change

💡 Additional Considerations

• The Edge cases in the same target still fail intermittently on error decoding response body from msedgedriver.microsoft.com, which is a download-side failure and not addressed here.

🔄 Types of changes

• Bug fix (backwards compatible)

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[qodo-code-review]

PR Summary by Qodo

Stabilize Rust browser tests on parallel runs and ARM64

🐞 Bug fix 🧪 Tests 🕐 Less than 10 minutes

AI Description

• Isolates fake Chrome executables per mismatch test to prevent parallel file overwrites.
• Skips unavailable legacy geckodriver cases on Linux ARM64 to avoid download failures.

Diagram

graph TD
  A["Version cases"] --> B{"Linux arm64?"} -- "Yes" --> C{"Artifact exists?"} -- "No" --> D["Skip case"]
  B -- "No" --> E["Run manager"]
  C -- "Yes" --> E
  F["Mismatch cases"] --> G["Private tempdir"] --> E

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High-Level Assessment

The PR uses the appropriate minimal fixes for both failure modes. Per-test temporary directories provide lifecycle-managed isolation without serializing the suite, while the ARM64 guard accurately avoids release artifacts that do not exist. Global unique filenames and forced test serialization were considered but provide weaker cleanup or reduce parallelism.

Files changed (1) +8 / -5

Bug fix (1) +8 / -5

browser_tests.rsIsolate fake browsers and skip unavailable ARM64 geckodrivers +8/-5

Isolate fake browsers and skip unavailable ARM64 geckodrivers

• Adds Firefox to the Linux ARM64 exclusion because the tested geckodriver versions predate ARM64 builds. Refactors fake-browser creation to use a caller-provided temporary directory, preventing parallel mismatch tests from overwriting a shared executable.

rust/tests/browser_tests.rs