[FIX #4227] AmbiguousBlockAssociation False Positive

[smakagon]

Fixes false positive of AmbiguousBlockAssociation cop reported in #4227

assert_equal site.posts.find { |p| p.title == "Foo Bar" }, results.first

[ashmaroli]

Thank you @smakagon for opening this PR. I tested this patch locally and found an additional false-alarm (which I had expected to be solved concurrently, so never included it in the issue ticket.)

While the following case is no longer flagged:

assert_equal site.posts.find { |p| p.title == "Foo Bar" }, results.first

The following is still flagged incorrectly...:

assert @site.pages.find { |page| page.data["date"] == date }

W: Parenthesize the param find to make sure that the block will be associated with the assert
method call.
      assert @site.pages.find { |page| page.data["date"] == date }
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

... and apparently, so is any call made by a receiver that is an instance_variable:

W: Parenthesize the param any? to make sure that the block will be associated with the assert
method call.
      assert @collection.docs.any? { |d| d.path.include?("all.dots") }
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

W: Parenthesize the param index to make sure that the block will be associated with the
refute_nil method call.
      refute_nil @site.posts.index { |post| ...
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[smakagon]

@ashmaroli
In your first example:

assert_equal site.posts.find { |p| p.title == "Foo Bar" }, results.first

You have 2 arguments for assert_equal function, so that block definitely belongs to find method and can not belong to assert_equal.

But with this example:
assert @site.pages.find { |page| page.data["date"] == date }

It's expected behavior because we can not say exactly if block belongs to find or assert. It's almost the same example that we had in description to initial issue:

some_method a { puts 1 }

For example Rspec users will get the same error for this code:
expect { order.expire }.to change { order.events }

If you don't want to add parentheses to those files It makes sense to disable this cop for tests/specs folder by adding this to .rubocop.yml file:

Lint/AmbiguousBlockAssociation:
  Exclude:
    - "spec/**/*"

[ashmaroli]

Thank you @smakagon for the prompt reply.
I tested again with corrections and indeed, the following is no longer flagged.

assert(@site.pages.find { |page| page.data["date"] == date })

👍

[bbatsov]

Just one small thing - you forgot to add a changelog entry.

[smakagon]

@bbatsov Thanks. Added Changelog entry.