Performance/AncestorsInclude shows warning for instance methods #ancestors

[klyonrad]

Calling a method with the name ancestors on an object raises the rubocop-performance warning.

Is this possible to detect more correctly with static code analysis or are we out of luck? If not, honestly I would question the usefulness of this cop because I don't think we are the only ones to happen to have data models where something is called ancestors.

---

Expected behavior

rubocop-performance only warns when .ancestors is called on a Class.
Calling of the instance method should be fine

Actual behavior

It seems to screem at any calling of something called .ancestors

Steps to reproduce the problem

We have a rails model with the following association declaration

has_many :ancestors

Somewhere we have a test where usage this method - on the instance.

expect(object_one.ancestors.include?(object_two)).to eq(true)

rubocop warns

Performance/AncestorsInclude: Use <= instead of ancestors.include?

RuboCop version

$ [bundle exec] rubocop -V
0.83.0 (using Parser 2.7.1.4, running on ruby 2.6.6 x86_64-darwin19)
# ...
ruby-2.6.6/gems/rubocop-performance-1.7.1

[marcandre]

@koic is working on a PR, but another way around is that this test could be improved to:

expect(object_one.ancestors).to include(object_two)

😄