Rubocop errors are not displayed in the VSCode

[cc-harashima]

Description

Ruby LSP Information

VS Code Version

1.96.0

Ruby LSP Extension Version

0.8.16

Ruby Version Manager

rbenv

gem Versions

rubocop 1.68.0
rubocop-rails 2.20.2

Reproduction steps

1. Start the Ruby LSP using a VSCode
2. Open or save a Specific Ruby file
3. An error notification within VSCode occurs as shown in the image below. Rubocop errors and warnings in that file are not displayed.

Code snippet or error message

Error running diagnostics: An internal error occurred for the Rails/UniqueValidationWithoutIndex cop. Updating to a newer version of RuboCop may solve this. For more details, run RuboCop on the command line.

Supplement

The same issue occurred with Rubocop 1.41.1 when using Ruby-LSP version 0.8.13. At that time, I upgraded Rubocop to version 1.68.0.

Constantly upgrading the Rubocop version increases the operational burden, which is challenging.

[andyw8]

For more details, run RuboCop on the command line.

Did you try this?

[cc-harashima]

For more details, run RuboCop on the command line.
Did you try this?

Yes. The rubocop command works correctly.
Some offenses are listed, but Rails/UniqueValidationWithoutIndex is not detected.

We use bundle exec command.

bundle exec rubocop app/target_file.rb

# ~~

1 file inspected, xx offenses detected, zz offenses autocorrectable

[vinistock]

Keep in mind that running RuboCop in the terminal is not representative of what's happening in the editor. When you're editing files, the Ruby LSP will constantly see files in their intermediate state as you are in the middle of typing.

When you run RuboCop in the terminal, you are likely already done editing, so in that environment RuboCop always sees the final form of the file.

These errors mean that the cop fails in some intermediate state. Maybe the implementation of the cop is making assumptions about certain parts of the code being present, which works on the command line, but will fail if you are in the middle of typing.

For example, imagine someone created a cop to verify that Rails' validate is always invoked with a method that is defined in that same model. If the cop assumes that the symbol representing the name of the method is always there, then it will certainly fail when running in the editor.

# The command line sees this. The complete version of the code
class Foo
  validate :something
end

# The LSP sees the entire progression of typing, one keypress at a time
# At a certain moment in time, no matter how fast you are typing, the LSP
# will see this code.
#
# In this case, you are typing the validate call, but haven't finished yet.
# If the cop assumes that validate will always have one argument with a symbol
# then it will crash in the editor
class Foo
  validate
end

If you can figure out under which conditions the cop crashes, then it would be nice to report it to rubocop-rails so that they can fix it.

From our side, I think we need to make the message clearer about when this notification pops up. And maybe it should be converted to a window log message, rather than a window show message.

[cc-harashima]

@vinistock

Thank you for the information.
I have confirmed that even when not in the middle of typing, RuboCop runs successfully on the command line, but an error dialog appears in the editor.

The Rails/UniqueValidationWithoutIndex cop should not be executed when db/schema.rb does not exist.
https://docs.rubocop.org/rubocop-rails/cops_rails.html#railsuniquevalidationwithoutindex

It is strange that this error is showing up on the LSP side, as db/schema.rb is not present in the current Rails project.