Fix relative file path verification on Windows

[Copilot]

• Identify CI build failure
• Fix netstandard2.0 compatibility issue (String.Contains with char vs string)
• Verify build passes
• Verify unit tests pass (123 tests, 0 failures)

Original prompt

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This section details on the original issue you should resolve

<issue_title>Relative file path verification fails on Windows</issue_title>
<issue_description>

Discussed in #278

^{Originally posted by Numpsy December 15, 2025}
Hi

I'm not sure if this is down to my environment or is an actual issue (I'm running on Windows and I see the CI is running on Ubuntu), but when I run the build script locally I get this unit test failure:

I got this when trying to do a local build for #277 and it prevented the later tests from running, making it harder to test.

Any ideas?

Thanks

</issue_description>

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

• Fixes Relative file path verification fails on Windows #280

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[sergey-tihon]

fix CI build

[Copilot]

fix CI build

Fixed in commit 3e1ed8b. The build was failing because String.Contains(char) is not available in netstandard2.0 - changed to use Contains(string) instead.

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I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/fsprojects/SwaggerProvider/actions/jobs/58875742271/logs
  • Triggering command: /usr/bin/curl curl -L REDACTED -H Accept: application/vnd.github.v3+json (http block)
• petstore.swagger.io
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet /usr/share/dotnet/sdk/10.0.101/FSharp/fsc.dll @/tmp/MSBuildTempBQPLYS/tmpada5e26978814a309e2a2d9c015b151b.rsp (dns block)

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[sergey-tihon]

@copilot fix tests

[Copilot]

@copilot fix tests

The unit tests (123 tests in SwaggerProvider.Tests) are passing successfully. However, the provider integration tests (SwaggerProvider.ProviderTests) are failing during compilation because the type providers need to fetch OpenAPI schemas from external URLs like petstore.swagger.io at compile time, and these network requests are timing out or being blocked.

This is a network/environment issue rather than a code issue with the relative path fix. The provider tests would need network access or local schema files to build successfully.

[Copilot]

Pull request overview

This PR fixes a Windows-specific issue where relative file path verification was failing when paths containing parent directory references (..) were concatenated with __SOURCE_DIRECTORY__. The fix introduces more nuanced path classification logic that correctly distinguishes between truly absolute paths and rooted paths with relative markers.

Key changes:

• Introduced startsWithRelativeMarker and isTrulyAbsolute helper functions to properly classify paths across Windows and Unix
• Modified getAbsolutePath to handle rooted paths with drive letters vs. rooted paths without drive letters differently
• Added comprehensive unit tests to verify path resolution behavior across platforms

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/SwaggerProvider.DesignTime/Utils.fs	Added helper functions startsWithRelativeMarker and isTrulyAbsolute to correctly identify absolute vs. relative paths; updated getAbsolutePath logic to handle Windows paths with drive letters and Unix paths with proper security checks for path traversal attempts
tests/SwaggerProvider.Tests/PathResolutionTests.fs	New test file with comprehensive coverage of path resolution scenarios including concatenated paths with parent directory references, relative paths, absolute paths (both Windows and Unix), URLs, and real-world __SOURCE_DIRECTORY__ usage patterns
tests/SwaggerProvider.Tests/SwaggerProvider.Tests.fsproj	Added reference to the new test file PathResolutionTests.fs in the compilation order

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