[Fixes #8626] Fix false negatives for Lint/UselessMethodDefinition.

Note that not calling `super` at all from `initialize` is left
to `Lint/MissingSuper` cop.

CHANGELOG.md

@@ -26,6 +26,7 @@
 * [#8688](https://github.com/rubocop-hq/rubocop/issues/8688): Mark `Style/GlobalStdStream` as unsafe autocorrection. ([@marcandre][])
 * [#8642](https://github.com/rubocop-hq/rubocop/issues/8642): Fix a false negative for `Style/SpaceInsideHashLiteralBraces` when a correct empty hash precedes the incorrect hash. ([@dvandersluis][])
 * [#8683](https://github.com/rubocop-hq/rubocop/issues/8683): Make naming cops work with non-ascii characters. ([@tejasbubane][])
+* [#8626](https://github.com/rubocop-hq/rubocop/issues/8626): Fix false negatives for `Lint/UselessMethodDefinition`. ([@marcandre][])
 
 ### Changes
 

docs/modules/ROOT/pages/cops_lint.adoc

@@ -4615,6 +4615,7 @@ an empty constructor just overrides the parent constructor, which is bad anyway.
 ----
 # bad
 def initialize
+  super
 end
 
 def method
@@ -4628,32 +4629,12 @@ end
 
 # good
 def initialize
-  initialize_internals
-end
-
-def method
   super
-  do_something_else
-end
-----
-
-==== AllowComments: true (default)
-
-[source,ruby]
-----
-# good
-def initialize
-  # Comment.
+  initialize_internals
 end
-----
 
-==== AllowComments: false
-
-[source,ruby]
-----
-# bad
-def initialize
-  # Comment.
+def method(*args)
+  super(:extra_arg, *args)
 end
 ----
 

lib/rubocop/cop/lint/useless_method_definition.rb

@@ -12,6 +12,7 @@ module Lint
       # @example
       #   # bad
       #   def initialize
+      #     super
       #   end
       #
       #   def method
@@ -25,24 +26,12 @@ module Lint
       #
       #   # good
       #   def initialize
-      #     initialize_internals
-      #   end
-      #
-      #   def method
       #     super
-      #     do_something_else
-      #   end
-      #
-      # @example AllowComments: true (default)
-      #   # good
-      #   def initialize
-      #     # Comment.
+      #     initialize_internals
       #   end
       #
-      # @example AllowComments: false
-      #   # bad
-      #   def initialize
-      #     # Comment.
+      #   def method(*args)
+      #     super(:extra_arg, *args)
       #   end
       #
       class UselessMethodDefinition < Base
@@ -52,8 +41,7 @@ class UselessMethodDefinition < Base
 
         def on_def(node)
           return if optional_args?(node)
-          return unless (constructor?(node) && empty_constructor?(node)) ||
-                        delegating?(node.body, node)
+          return unless delegating?(node.body, node)
 
           add_offense(node) { |corrector| corrector.remove(node) }
         end
@@ -65,21 +53,16 @@ def optional_args?(node)
           node.arguments.any? { |arg| arg.optarg_type? || arg.kwoptarg_type? }
         end
 
-        def empty_constructor?(node)
-          return false if node.body
-          return false if cop_config['AllowComments'] && comment_lines?(node)
-
-          true
-        end
-
-        def constructor?(node)
-          node.def_type? && node.method?(:initialize)
-        end
-
         def delegating?(node, def_node)
-          return false unless node&.super_type? || node&.zsuper_type?
-
-          !node.arguments? || node.arguments.map(&:source) == def_node.arguments.map(&:source)
+          if node.nil?
+            false
+          elsif node.zsuper_type?
+            true
+          elsif node.super_type?
+            node.arguments.map(&:source) == def_node.arguments.map(&:source)
+          else
+            false
+          end
         end
       end
     end

spec/rubocop/cop/lint/useless_method_definition_spec.rb

@@ -7,20 +7,13 @@
     { 'AllowComments' => true }
   end
 
-  it 'registers an offense and corrects for empty constructor' do
-    expect_offense(<<~RUBY)
+  it 'does not register an offense for empty constructor' do
+    expect_no_offenses(<<~RUBY)
       class Foo
         def initialize(arg1, arg2)
-        ^^^^^^^^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
         end
       end
     RUBY
-
-    expect_correction(<<~RUBY)
-      class Foo
-       #{trailing_whitespace}
-      end
-    RUBY
   end
 
   it 'does not register an offense for constructor with only comments' do
@@ -88,6 +81,11 @@ def other_class_method
             super
           end
 
+          def other_class_method_with_parens
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
+            super()
+          end
+
           def other_class_method_with_args(arg)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Useless method definition detected.
             super(arg)
@@ -122,6 +120,8 @@ def self.other_useful_class_method
          #{trailing_whitespace}
 
          #{trailing_whitespace}
+
+         #{trailing_whitespace}
         end
       end
     RUBY
@@ -145,6 +145,10 @@ def method1(foo)
       def method2(foo, bar)
         super(bar, foo)
       end
+
+      def method3(foo, bar)
+        super()
+      end
     RUBY
   end
 
@@ -171,27 +175,4 @@ def non_constructor
       end
     RUBY
   end
-
-  context 'when AllowComments is false' do
-    let(:cop_config) do
-      { 'AllowComments' => false }
-    end
-
-    it 'registers an offense when constructor contains only comments' do
-      expect_offense(<<~RUBY)
-        class Foo
-          def initialize
-          ^^^^^^^^^^^^^^ Useless method definition detected.
-            # Comment.
-          end
-        end
-      RUBY
-
-      expect_correction(<<~RUBY)
-        class Foo
-         #{trailing_whitespace}
-        end
-      RUBY
-    end
-  end
 end