Linter should ignore `__tests__` folder when invoking `@lwc/metadata`

[nolanlawson]

Summary

Users are reporting (salesforce/sfdx-lwc-jest#350) that import { createElement } from 'lwc' is showing a red squiggly in VS Code even though this is not considered a lint error anywhere else in the system (e.g. when running eslint on the command line or publishing via SFDX).

Our team looked into this, and we believe the solution is the following:

• The compiler ignores files that are in __tests__ folder and hence the linting rules do not apply. That explains why they are not facing any issues when saving the component.
• The fix would be to make language server mimic the same and ignore tests folder when invoking @lwc/metadata.

Steps To Reproduce:

1. Add import { createElement } from 'lwc' to a __tests__ (Jest) test in an SFDX project.

Expected result

No red squiggly should appear.

Actual result

A red squiggly appears.

Additional information

Please see salesforce/sfdx-lwc-jest#350 for the original bug report.

VS Code Version: Unknown

SFDX CLI Version: Unknown

OS and version: Unknown

[BatemanVO]

As requested from the previous thread:
VS Code Version: 1.86.2, x64
SFDX CLI Version: 2.29.5
OS and version: Windows 10 22H2 Build 19045.4046

[erocheleau]

Same

• VS Code Version: 1.85.1 (Universal)
  
• sf-cli version: @salesforce/cli/2.25.7 darwin-arm64 node-v18.19.0
• OS: macOS Sonoma 14.2.1 (Apple M2 Max)

[EmilynPantelakis]

I'm here to report the same issue.

• VS Code Version:
  
• sf cli version: @salesforce/cli/2.9.8
• OS: Windows 11 Pro x64

[BaswarajTandur]

@nolanlawson
what's the solution for this, I'm facing the same issue.

[GH4Arlene]

The impact of this is that the sheer number of errors masks any real errors we might need to see, and slows down VSCode for quite a while on startup.

[b-bell]

Reporting the same issue. As outlined above, the issue appears from the auto-generated files in __test__.

• VS Code Version: 1.99.2
• SFDX CLI Version: 2.83.7
• OS: maxOS Sequoia 15.4 (Apple M1 Pro)

Changing lwc to lwc/ resolved the error as outlined by the highest voted comment on the Trailblazer Community.

This Stack Exchange thread and the thread of both also say import { createElement } from '@lwc/engine-dom'; resolved the error.