[xperiandri]

Summary

A solution in the .slnx format (the XML based solution format that the .NET SDK 9.0.200 and later and MSBuild 17.13 and later read) is not recognized by the extension as a solution file. For such a solution, a change of the solution file, such as adding a project, does not reload the list of .resx files. The watcher of the project files is not affected.

This pull request makes the watcher and the handler of renamed files accept .sln and .slnx, without regard to case, and adds nine tests for the new helper.

Cause, changes, things to know and verification

Cause

StringResVizPackage sets up the watcher of the solution file only when the name ends in .sln, and the handler of renamed files checks the same. For a .slnx solution that watcher is never set up.

Changes

• StringExtensions.IsSolutionFileName recognizes the .sln and .slnx extensions, without regard to case.
• WatchForSolutionOrProjectChanges and SlnWatcher_Renamed use it. The check in the rename handler compared case sensitively before and does not any more.
• Nine tests for the helper in a new StringExtensionsTests class: both formats, different case, a project file, a solution filter, an extension in the middle of the path, an empty name and null.

Things to know

• This was found while converting the solution of this repository to .slnx, which is Switch the solution to the .slnx format #53 now (the earlier Add instructions and configuration for AI coding agents #50 was closed in favor of the chain Switch the solution to the .slnx format #53 to Build with dotnet build #58). This pull request and the chain are independent of each other.
• Convert the projects to the SDK style #55 converts the test project to the SDK style, where the line <Compile Include="StringExtensionsTests.cs" /> that this pull request adds is not needed, so whichever of the two is merged second needs a trivial rebase.

Verification

• A full rebuild gives no errors and the same 26 distinct warnings as the code without the change. It was built with the MSBuild of Visual Studio 2026 and -p:TargetFrameworkVersion=v4.8, because the .NET Framework 4.8.1 targeting pack is not installed on the machine that prepared this change. All 13 tests pass: the 4 existing ones and the 9 new ones.
• The extension was not run in the Experimental instance, so the watcher itself is not exercised by a test. To see it work, open a solution in the .slnx format and change the solution file (for example by adding a project): the "String Resource Visualizer" pane of the Output window should then show "Reloading list of resx files.".
• CI: the workflow of this repository waits for the approval of a maintainer on this pull request. The same branch ran in a fork (Build). The build, with the .NET Framework 4.8.1 targeting pack of the runner, and the test step succeed. The step Publish Test Results then fails, because the third-party action EnricoMi/publish-unit-test-result-action/windows@v2 finds no Python interpreter on the windows-2022 image (No python3 interpreter found); it fails in the same way on the unchanged code of main (run in the fork), so this change does not cause it.

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