[Bug]: Test discovery breaks when parent and nested folders are both in the workspace

[tmcgannon]

Checklist

• I have read and agree to the Code of Conduct
• I have searched for related issues and discussions but they did not match this problem.
• I want to contribute a bugfix myself.

Actual behavior

Hi! I’ve run into a test discovery problem with a multi-root VS Code workspace.

My repository has a server package with its own .mocharc.cjs. Everything works when I open only the server folder: mocha-vscode finds the correct Mocha installation and discovers the full test suite (around 3,200 tests).

The problem appears when I open a workspace containing both the repository root and the nested server folder.

For now, my workaround is to use a separate workspace containing only the server folder.

Thanks for taking a look!

Expected behavior

I’d expect server/.mocharc.cjs to be registered once, preferably using the nested server workspace folder as its context.

Ideally, the same setup would work whether I open:

• Only the server folder
• A multi-root workspace containing both server and its parent repository

Minimal, Reproducible Example

Workspace setup

This works:

{
  "folders": [
    {
      "name": "Server",
      "path": "server"
    }
  ]
}

This does not:

{
  "folders": [
    {
      "name": "Server",
      "path": "server"
    },
    {
      "name": "Repository",
      "path": "."
    }
  ]
}

The relevant layout is:

repo/
  project.code-workspace
  server/
    .mocharc.cjs
    package.json

What happens

Both workspace folders seem to find the same Mocha config:

New Test Controller for workspace folder and config /path/to/repo/server /path/to/repo/server/.mocharc.cjs
New Test Controller for workspace folder and config /path/to/repo /path/to/repo/server/.mocharc.cjs

The second registration then fails:

Error: Attempt to insert a duplicate controller with ID "file:///path/to/repo/server/.mocharc.cjs"
    at ...createTestController...
    at ...coderline.mocha-vscode-1.4.0/out/extension.js...
    at ...addConfigFile...

After that, the Testing view either shows no tests or only part of the suite. It can also appear to resolve Mocha from the wrong workspace-folder context.

I can reproduce the duplicate-controller error especially reliably by creating, moving, or recreating server/.mocharc.cjs while the multi-root workspace is open.

Output

The second registration then fails:

Error: Attempt to insert a duplicate controller with ID "file:///path/to/repo/server/.mocharc.cjs"
    at ...createTestController...
    at ...coderline.mocha-vscode-1.4.0/out/extension.js...
    at ...addConfigFile...

Plugin Version Details

Environment

• mocha-vscode: 1.4.0
• Extension build: v1.4.0+bd847bf
• VS Code: 1.137.0
• macOS, arm64
• Node.js: 24.18.0
• Mocha: 11.8.0

VS Code Version Details

• VS Code: 1.137.0

Further details

No response