From 9ceb446f41c47e28201d9b601fd2ff572d20c1cb Mon Sep 17 00:00:00 2001
From: fatkodima <fatkodima123@gmail.com>
Date: Wed, 28 Oct 2020 03:11:51 +0200
Subject: [PATCH] Support arguments forwarding in `Lint/ToEnumArguments` cop
 (#8961)

---
 lib/rubocop/cop/lint/to_enum_arguments.rb     |  3 ++-
 lib/rubocop/rspec/shared_contexts.rb          |  4 ++++
 .../cop/lint/to_enum_arguments_spec.rb        | 23 ++++++++++++++++---
 3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/lib/rubocop/cop/lint/to_enum_arguments.rb b/lib/rubocop/cop/lint/to_enum_arguments.rb
index 4fc8df8a7358..fd6135cfb4af 100644
--- a/lib/rubocop/cop/lint/to_enum_arguments.rb
+++ b/lib/rubocop/cop/lint/to_enum_arguments.rb
@@ -44,7 +44,6 @@ class ToEnumArguments < Base
           (pair (sym %1) (lvar %1))
         PATTERN
 
-        # TODO: add support for argument forwarding (`...`) when ruby 3.0 is released
         def on_send(node)
           def_node = node.each_ancestor(:def, :defs).first
           return unless def_node
@@ -85,6 +84,8 @@ def argument_match?(send_arg, def_arg)
               send_arg.pairs.any? { |pair| passing_keyword_arg?(pair, def_arg_name) }
           when :kwrestarg
             send_arg.each_child_node(:kwsplat).any? { |child| child.source == def_arg.source }
+          when :forward_arg
+            send_arg.forwarded_args_type?
           end
         end
         # rubocop:enable Metrics/AbcSize, Metrics/CyclomaticComplexity
diff --git a/lib/rubocop/rspec/shared_contexts.rb b/lib/rubocop/rspec/shared_contexts.rb
index e7367814c473..1e250a01e8a7 100644
--- a/lib/rubocop/rspec/shared_contexts.rb
+++ b/lib/rubocop/rspec/shared_contexts.rb
@@ -138,3 +138,7 @@ def source_range(range, buffer: source_buffer)
 RSpec.shared_context 'ruby 2.7', :ruby27 do
   let(:ruby_version) { 2.7 }
 end
+
+RSpec.shared_context 'ruby 3.0', :ruby30 do
+  let(:ruby_version) { 3.0 }
+end
diff --git a/spec/rubocop/cop/lint/to_enum_arguments_spec.rb b/spec/rubocop/cop/lint/to_enum_arguments_spec.rb
index 39a3ac0b5cc8..adc452270662 100644
--- a/spec/rubocop/cop/lint/to_enum_arguments_spec.rb
+++ b/spec/rubocop/cop/lint/to_enum_arguments_spec.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe RuboCop::Cop::Lint::ToEnumArguments do
-  subject(:cop) { described_class.new }
-
+RSpec.describe RuboCop::Cop::Lint::ToEnumArguments, :config do
   it 'registers an offense when required arg is missing' do
     expect_offense(<<~RUBY)
       def m(x)
@@ -131,4 +129,23 @@ def m(x, y = 1, *args, required:, optional: true, **kwargs, &block)
       end
     RUBY
   end
+
+  context 'arguments forwarding', :ruby30 do
+    it 'registers an offense when enumerator is created with non matching arguments' do
+      expect_offense(<<~RUBY)
+        def m(...)
+          return to_enum(:m, x, ...) unless block_given?
+                 ^^^^^^^^^^^^^^^^^^^ Ensure you correctly provided all the arguments.
+        end
+      RUBY
+    end
+
+    it 'does not register an offense when enumerator is created with the correct arguments' do
+      expect_no_offenses(<<~RUBY)
+        def m(...)
+          return to_enum(:m, ...) unless block_given?
+        end
+      RUBY
+    end
+  end
 end