Style/LambdaCall skips subsequent checks after finding a violation

[sswander]

My colleague @kelvinngsl and I might have found an unexpected behaviour in Style/LambdaCall. It might also be related to Style/LambdaCall's implementation of ConfigurableEnforcedStyle mixin.

With EnforcedStyle: braces, when the first blk.call is found, it is reported as an offense, but all subsequent code that violates the braces code style got skipped.

With EnforcedStyle: call, when the first blk.() is found, it is reported as an offense, but all subsequent code that violates the braces code style got skipped.

I have included example and steps to reproduce in the section below.

Some finding that might be helpful:

• Looking at the source code, I think this is related to the use of opposite_style_detected in lib/rubocop/cop/style/lambda_call.rb. Once an opposite style is detected, the ConfigurableEnforcedStyle mixin turned the config into { 'Enabled' => false }, thus ignoring any subsequent violations.

If this is indeed an issue, I am willing to give fixing it a try. However I'm not really sure where to start, so some pointer would be appreciated 🙇

---

• I've searched open issues and it does not seem that this is already reported.
• I've checked https://github.com/rubocop-hq/rubocop/blob/master/lib/rubocop/cop/style/lambda_call.rb and it is the same as the rubocop in my machine (1.5.2).

---

Expected behavior

RuboCop should detect all blk.call violations when EnforcedStyle: braces. Conversely, RuboCop should detect all blk.() violations when EnforcedStyle: call.

Actual behavior

It seems that once RuboCop found the first violation, the rest of the violations get ignored, so not all of the violations end up getting reported.

Steps to reproduce the problem

The following example illustrates an exaggeration of the unexpected behaviour by adding an inline disable. The root cause should be as reported above, which is RuboCop ignoring subsequent violations.

The following example uses EnforcedStyle: braces. However, the same behaviour also happens with EnforcedStyle: call and when the codebase uses the opposite pattern.

rubocop.yml:

Style/LambdaCall:
  EnforcedStyle: braces

test.rb:

def test1(&blk)
  blk.()
end

def test2(&blk)
  blk.call # rubocop:disable Style/LambdaCall
end

def test3(&blk)
  blk.call
end

def test4(&blk)
  blk.call
end

RuboCop result:

$ bundle exec rubocop test.rb

Inspecting 1 file
.

1 file inspected, no offenses detected

RuboCop version

$ bundle exec rubocop -V
1.5.2 (using Parser 2.7.2.0, rubocop-ast 1.3.0, running on ruby 2.6.6 x86_64-darwin18)

[fatkodima]

@sswander You should move opposite_style_detected into add_offense
https://github.com/rubocop-hq/rubocop/blob/b01dcfc27db16010707e8e2d4c5627612c6e21b7/lib/rubocop/cop/style/lambda_call.rb#L30-L36

as

if offense?(node)
  add_offense(node) do |corrector|
    opposite_style_detected
    autocorrect(corrector, node)
  end
else
  correct_style_detected
end

and add a test case with producing 2 violations at the same time.

[sswander]

@fatkodima nice, thanks for the pointer! I'll give this a try 👍