Fix false positives for Style/HashEachMethods

Fixes #12534 (comment). This PR fixes false positives for `Style/HashEachMethods` when using array converter method. Hash object converted to an Array cannot process `Hash#each_key` and `Hash#each_value`. Therefore, if methods that convert to an Array are used before `each`, they should be ignored.
rubocop · Jan 23, 2024 · 05730f5 · 05730f5
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diff --git a/changelog/fix_false_positives_for_style_hash_each_methods_when_array_converter.md b/changelog/fix_false_positives_for_style_hash_each_methods_when_array_converter.md
@@ -0,0 +1 @@
+* [#12642](https://github.com/rubocop/rubocop/pull/12642): Fix false positives for `Style/HashEachMethods` when using array converter method. ([@koic][])
diff --git a/lib/rubocop/cop/style/hash_each_methods.rb b/lib/rubocop/cop/style/hash_each_methods.rb
@@ -40,6 +40,7 @@ class HashEachMethods < Base
 
         MSG = 'Use `%<prefer>s` instead of `%<current>s`.'
         UNUSED_BLOCK_ARG_MSG = "#{MSG.chop} and remove the unused `%<unused_code>s` block argument."
+        ARRAY_CONVERTER_METHODS = %i[assoc flatten rassoc sort sort_by to_a].freeze
 
         # @!method kv_each(node)
         def_node_matcher :kv_each, <<~PATTERN
@@ -100,6 +101,7 @@ def on_block_pass(node)
         private
 
         def handleable?(node)
+          return false if use_array_converter_method_as_preceding?(node)
           return false unless (root_receiver = root_receiver(node))
 
           !root_receiver.literal? || root_receiver.hash_type?
@@ -152,6 +154,16 @@ def register_kv_with_block_pass_offense(node, target, method)
           end
         end
 
+        def use_array_converter_method_as_preceding?(node)
+          return false unless (preceding_method = node.children.first.children.first)
+          unless preceding_method.call_type? ||
+                 preceding_method.block_type? || preceding_method.numblock_type?
+            return false
+          end
+
+          ARRAY_CONVERTER_METHODS.include?(preceding_method.method_name)
+        end
+
         def root_receiver(node)
           receiver = node.receiver
           if receiver&.receiver

diff --git a/spec/rubocop/cop/style/hash_each_methods_spec.rb b/spec/rubocop/cop/style/hash_each_methods_spec.rb
@@ -179,6 +179,54 @@
         RUBY
       end
 
+      it 'does not register an offense when the key block argument of `Enumerable#each` method is unused after `assoc`' do
+        expect_no_offenses(<<~RUBY)
+          foo.assoc(key).each { |unused_key, v| do_something(v) }
+        RUBY
+      end
+
+      it 'does not register an offense when the key block argument of `Enumerable#each` method is unused after `flatten`' do
+        expect_no_offenses(<<~RUBY)
+          foo.flatten.each { |unused_key, v| do_something(v) }
+        RUBY
+      end
+
+      it 'does not register an offense when the key block argument of `Enumerable#each` method is unused after `rassoc`' do
+        expect_no_offenses(<<~RUBY)
+          foo.rassoc(value).each { |unused_key, v| do_something(v) }
+        RUBY
+      end
+
+      it 'does not register an offense when the key block argument of `Enumerable#each` method is unused after `sort`' do
+        expect_no_offenses(<<~RUBY)
+          foo.sort.each { |unused_key, v| do_something(v) }
+        RUBY
+      end
+
+      it 'does not register an offense when the key block argument of `Enumerable#each` method is unused after `sort_by`' do
+        expect_no_offenses(<<~RUBY)
+          foo.sort_by { |k, v| v }.each { |unused_key, v| do_something(v) }
+        RUBY
+      end
+
+      it 'does not register an offense when the key block argument of `Enumerable#each` method is unused after `sort_by` with numblock' do
+        expect_no_offenses(<<~RUBY)
+          foo.sort_by { _2 }.each { |unused_key, v| do_something(v) }
+        RUBY
+      end
+
+      it 'does not register an offense when the key block argument of `Enumerable#each` method is unused after `to_a`' do
+        expect_no_offenses(<<~RUBY)
+          foo.to_a.each { |unused_key, v| do_something(v) }
+        RUBY
+      end
+
+      it 'does not register an offense when the key block argument of `Enumerable#each` method is unused after `to_a` with safe navigation' do
+        expect_no_offenses(<<~RUBY)
+          foo&.to_a.each { |unused_key, v| do_something(v) }
+        RUBY
+      end
+
       it 'registers an offense when the destructed key block argument of `Enumerable#each` method is unused' do
         expect_offense(<<~RUBY)
           foo.each { |(_, unused_key), v| do_something(v) }
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		* [#12642](https://github.com/rubocop/rubocop/pull/12642): Fix false positives for `Style/HashEachMethods` when using array converter method. ([@koic][])