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Fix an error for Lint/ErbNewArguments cop #7806

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merged 1 commit into from Mar 21, 2020

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@koic koic commented Mar 21, 2020

This PR fixes the following error for Lint/ErbNewArguments cop when inspecting ActionView::Template::Handlers::ERB.new.

% cd path/to/rails/rails # rails/rails@f265e0dd
% bundle exec rubocop -d --only Lint/ErbNewArguments
actionview/lib/action_view/template/handlers.rb
For /Users/koic/src/github.com/rails/rails: configuration from
/Users/koic/src/github.com/rubocop-hq/rubocop/config/default.yml
Inspecting 1 file
Scanning
/Users/koic/src/github.com/rails/rails/actionview/lib/action_view/template/handlers.rb
An error occurred while Lint/ErbNewArguments cop was inspecting
/Users/koic/src/github.com/rails/rails/actionview/lib/action_view/template/handlers.rb:14:45.
undefined method `each_with_index' for nil:NilClass
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/cop/lint/erb_new_arguments.rb:89:in
`block in on_send'
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/cop/lint/erb_new_arguments.rb:90:in
`erb_new_with_non_keyword_arguments'
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/cop/lint/erb_new_arguments.rb:86:in
`on_send'

ActionView::Template::Handlers::ERB accepts new method without arguments, unlike standard ERB.

Below is the code that caused the error.

base.register_template_handler :erb, ERB.new

https://github.com/rails/rails/blob/v6.0.2.2/actionview/lib/action_view/template/handlers.rb#L16

It is an error if the standard ERB.new without arguments is used.
Therefore standard ERB.new and ActionView::Template::Handlers::ERB.new do not conflict.

% ruby -rerb -ve 'ERB.new'
ruby 2.7.0p0 (2019-12-25 revision 647ee6f091) [x86_64-darwin17]
Traceback (most recent call last):
        2: from -e:1:in `<main>'
        1: from -e:1:in `new'
/Users/koic/.rbenv/versions/2.7.0/lib/ruby/2.7.0/erb.rb:809:in
`initialize': wrong number of arguments (given 0, expected 1..4) (ArgumentError)

So including this patch in the cop will not interfere with linting to standard ERB.


Before submitting the PR make sure the following are checked:

  • Wrote good commit messages.
  • Commit message starts with [Fix #issue-number] (if the related issue exists).
  • Feature branch is up-to-date with master (if not - rebase it).
  • Squashed related commits together.
  • Added tests.
  • Added an entry to the Changelog if the new code introduces user-observable changes. See changelog entry format.
  • The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
  • Run bundle exec rake default. It executes all tests and RuboCop for itself, and generates the documentation.

This PR fixes the following error for `Lint/ErbNewArguments` cop
when inspecting `ActionView::Template::Handlers::ERB.new`.

```console
% cd path/to/rails/rails # rails/rails@f265e0dd
% bundle exec rubocop -d --only Lint/ErbNewArguments
actionview/lib/action_view/template/handlers.rb
For /Users/koic/src/github.com/rails/rails: configuration from
/Users/koic/src/github.com/rubocop-hq/rubocop/config/default.yml
Inspecting 1 file
Scanning
/Users/koic/src/github.com/rails/rails/actionview/lib/action_view/template/handlers.rb
An error occurred while Lint/ErbNewArguments cop was inspecting
/Users/koic/src/github.com/rails/rails/actionview/lib/action_view/template/handlers.rb:14:45.
undefined method `each_with_index' for nil:NilClass
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/cop/lint/erb_new_arguments.rb:89:in
`block in on_send'
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/cop/lint/erb_new_arguments.rb:90:in
`erb_new_with_non_keyword_arguments'
/Users/koic/src/github.com/rubocop-hq/rubocop/lib/rubocop/cop/lint/erb_new_arguments.rb:86:in
`on_send'
```

`ActionView::Template::Handlers::ERB` accepts `new` method without arguments,
unlike standard `ERB`.

Below is the code that caused the error.

```ruby
base.register_template_handler :erb, ERB.new
```

https://github.com/rails/rails/blob/v6.0.2.2/actionview/lib/action_view/template/handlers.rb#L16

It is an error if the standard `ERB.new` without arguments is used.
Therefore standard `ERB.new` and `ActionView::Template::Handlers::ERB.new`
do not conflict.

```console
% ruby -rerb -ve 'ERB.new'
ruby 2.7.0p0 (2019-12-25 revision 647ee6f091) [x86_64-darwin17]
Traceback (most recent call last):
        2: from -e:1:in `<main>'
        1: from -e:1:in `new'
/Users/koic/.rbenv/versions/2.7.0/lib/ruby/2.7.0/erb.rb:809:in
`initialize': wrong number of arguments (given 0, expected 1..4) (ArgumentError)
```

So including this patch in the cop will not interfere with linting to standard `ERB`.
@koic koic force-pushed the fix_error_for_lint_erb_new_arguments branch from 43182ea to ab5144a Compare Mar 21, 2020
@bbatsov bbatsov merged commit 0aa2e59 into rubocop:master Mar 21, 2020
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bbatsov commented Mar 21, 2020

Thanks!

@koic koic deleted the fix_error_for_lint_erb_new_arguments branch Mar 21, 2020
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