[denizumur]

Summary

Closes #46.

The FluentValidation test suite currently depends on the host machine's UI culture for tests that assert exact English validation messages.

This PR makes those tests deterministic without changing production behavior or FluentValidation localization.

Changes

• Added a reusable UseCultureAttribute based on xUnit's BeforeAfterTestAttribute
• Applied en-US to test classes that assert exact English validation messages
• Enabled TestServer.PreserveExecutionContext for the shared server test host so request execution preserves the selected test culture
• Kept Messages_are_localized_by_fluent_validation unchanged so explicit Turkish localization behavior remains covered

Validation

Reproduced under tr-TR before the fix:

• .NET 6: 21 passed, 9 failed
• .NET 8: 21 passed, 7 failed
• .NET 10: 21 passed, 7 failed

After the fix:

• .NET 6: 30/30 FluentValidation tests passed
• .NET 8: 28/28 FluentValidation tests passed
• .NET 10: 28/28 FluentValidation tests passed
• Full solution tests passed on .NET 6, 8, and 10
• git diff --check passed

.NET Core 3.1 builds successfully but could not be executed locally because the .NET Core 3.1 runtime is not installed.

No production code, validation messages, or package references were changed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sinanbozkus]

Thanks a lot for the report and the clean fix, @denizumur! Merged. Welcome aboard as a contributor 🎉

[denizumur]

Thank you! I really appreciate the review and the warm welcome. Happy to contribute — looking forward to helping again in the future! 🙌