Updated Gemspec/RequiredRubyVersion register an offense when set to…

… blank values.

changelog/change_updated_gemspecrequiredrubyversion_to.md

@@ -0,0 +1 @@
+* [#10157](https://github.com/rubocop/rubocop/pull/10157): Updated `Gemspec/RequiredRubyVersion` handle being set to blank values. ([@dvandersluis][])

config/default.yml

@@ -262,7 +262,7 @@ Gemspec/RequiredRubyVersion:
   Description: 'Checks that `required_ruby_version` of gemspec is specified and equal to `TargetRubyVersion` of .rubocop.yml.'
   Enabled: true
   VersionAdded: '0.52'
-  VersionChanged: '0.89'
+  VersionChanged: '<<next>>'
   Include:
     - '**/*.gemspec'
 

lib/rubocop/cop/gemspec/required_ruby_version.rb

@@ -3,10 +3,11 @@
 module RuboCop
   module Cop
     module Gemspec
-      # Checks that `required_ruby_version` of gemspec is specified and
-      # equal to `TargetRubyVersion` of .rubocop.yml.
-      # Thereby, RuboCop to perform static analysis working on the version
-      # required by gemspec.
+      # Checks that `required_ruby_version` in a gemspec file is set to a valid
+      # value (non-blank) and matches `TargetRubyVersion` as set in RuboCop's
+      # configuration for the gem.
+      #
+      # This ensures that RuboCop is using the same Ruby version as the gem.
       #
       # @example
       #   # When `TargetRubyVersion` of .rubocop.yml is `2.5`.
@@ -26,6 +27,11 @@ module Gemspec
       #     spec.required_ruby_version = '>= 2.6.0'
       #   end
       #
+      #   # bad
+      #   Gem::Specification.new do |spec|
+      #     spec.required_ruby_version = ''
+      #   end
+      #
       #   # good
       #   Gem::Specification.new do |spec|
       #     spec.required_ruby_version = '>= 2.5.0'
@@ -49,15 +55,15 @@ module Gemspec
       class RequiredRubyVersion < Base
         include RangeHelp
 
-        NOT_EQUAL_MSG = '`required_ruby_version` (%<required_ruby_version>s, ' \
-                        'declared in %<gemspec_filename>s) and `TargetRubyVersion` ' \
+        RESTRICT_ON_SEND = %i[required_ruby_version=].freeze
+        NOT_EQUAL_MSG = '`required_ruby_version` and `TargetRubyVersion` ' \
                         '(%<target_ruby_version>s, which may be specified in ' \
                         '.rubocop.yml) should be equal.'
         MISSING_MSG = '`required_ruby_version` should be specified.'
 
-        # @!method required_ruby_version(node)
-        def_node_search :required_ruby_version, <<~PATTERN
-          (send _ :required_ruby_version= $_)
+        # @!method required_ruby_version?(node)
+        def_node_search :required_ruby_version?, <<~PATTERN
+          (send _ :required_ruby_version= _)
         PATTERN
 
         # @!method defined_ruby_version(node)
@@ -66,27 +72,28 @@ class RequiredRubyVersion < Base
             (send (const (const nil? :Gem) :Requirement) :new $(str _))}
         PATTERN
 
-        # rubocop:disable Metrics/AbcSize
         def on_new_investigation
-          version_def = required_ruby_version(processed_source.ast).first
+          add_global_offense(MISSING_MSG) unless required_ruby_version?(processed_source.ast)
+        end
 
-          if version_def
-            ruby_version = extract_ruby_version(defined_ruby_version(version_def))
-            return if !ruby_version || ruby_version == target_ruby_version.to_s
+        def on_send(node)
+          version_def = node.first_argument
+          return if dynamic_version?(version_def)
 
-            add_offense(
-              version_def.loc.expression,
-              message: not_equal_message(ruby_version, target_ruby_version)
-            )
-          else
-            range = source_range(processed_source.buffer, 1, 0)
-            add_offense(range, message: MISSING_MSG)
-          end
+          ruby_version = extract_ruby_version(defined_ruby_version(version_def))
+          return if ruby_version == target_ruby_version.to_s
+
+          add_offense(version_def, message: not_equal_message(ruby_version, target_ruby_version))
         end
-        # rubocop:enable Metrics/AbcSize
 
         private
 
+        def dynamic_version?(node)
+          (node.send_type? && !node.receiver) ||
+            node.variable? ||
+            node.each_descendant(:send, *RuboCop::AST::Node::VARIABLES).any?
+        end
+
         def extract_ruby_version(required_ruby_version)
           return unless required_ruby_version
 

spec/rubocop/cop/gemspec/duplicated_assignment_spec.rb

@@ -33,6 +33,16 @@
     RUBY
   end
 
+  it 'registers an offense when using `required_ruby_version=` twice' do
+    expect_offense(<<~RUBY)
+      ::Gem::Specification.new do |spec|
+        spec.required_ruby_version = '2.5'
+        spec.required_ruby_version = '2.6'
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `required_ruby_version=` method calls already given on line 2 of the gemspec.
+      end
+    RUBY
+  end
+
   it 'does not register an offense when using `<<` twice' do
     expect_no_offenses(<<~RUBY)
       Gem::Specification.new do |spec|

spec/rubocop/cop/gemspec/required_ruby_version_spec.rb

@@ -6,7 +6,7 @@
       expect_offense(<<~RUBY, '/path/to/foo.gemspec')
         Gem::Specification.new do |spec|
           spec.required_ruby_version = '>= 2.6.0'
-                                       ^^^^^^^^^^ `required_ruby_version` (2.6, declared in foo.gemspec) and `TargetRubyVersion` (2.7, which may be specified in .rubocop.yml) should be equal.
+                                       ^^^^^^^^^^ `required_ruby_version` and `TargetRubyVersion` (2.7, which may be specified in .rubocop.yml) should be equal.
         end
       RUBY
     end
@@ -15,7 +15,7 @@
       expect_offense(<<~RUBY, '/path/to/foo.gemspec')
         Gem::Specification.new do |spec|
           spec.required_ruby_version = '~> 2.6.0'
-                                       ^^^^^^^^^^ `required_ruby_version` (2.6, declared in foo.gemspec) and `TargetRubyVersion` (2.7, which may be specified in .rubocop.yml) should be equal.
+                                       ^^^^^^^^^^ `required_ruby_version` and `TargetRubyVersion` (2.7, which may be specified in .rubocop.yml) should be equal.
         end
       RUBY
     end
@@ -24,7 +24,7 @@
       expect_offense(<<~RUBY, '/path/to/foo.gemspec')
         Gem::Specification.new do |spec|
           spec.required_ruby_version = ['>= 2.6.0', '< 3.0.0']
-                                       ^^^^^^^^^^^^^^^^^^^^^^^ `required_ruby_version` (2.6, declared in foo.gemspec) and `TargetRubyVersion` (2.7, which may be specified in .rubocop.yml) should be equal.
+                                       ^^^^^^^^^^^^^^^^^^^^^^^ `required_ruby_version` and `TargetRubyVersion` (2.7, which may be specified in .rubocop.yml) should be equal.
         end
       RUBY
     end
@@ -33,7 +33,7 @@
       expect_offense(<<~RUBY, '/path/to/foo.gemspec')
         Gem::Specification.new do |spec|
           spec.required_ruby_version = Gem::Requirement.new(">= 2.6.0")
-                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `required_ruby_version` (2.6, declared in foo.gemspec) and `TargetRubyVersion` (2.7, which may be specified in .rubocop.yml) should be equal.
+                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `required_ruby_version` and `TargetRubyVersion` (2.7, which may be specified in .rubocop.yml) should be equal.
         end
       RUBY
     end
@@ -67,7 +67,7 @@
       expect_offense(<<~RUBY, '/path/to/bar.gemspec')
         Gem::Specification.new do |spec|
           spec.required_ruby_version = '>= 2.6.0'
-                                       ^^^^^^^^^^ `required_ruby_version` (2.6, declared in bar.gemspec) and `TargetRubyVersion` (2.5, which may be specified in .rubocop.yml) should be equal.
+                                       ^^^^^^^^^^ `required_ruby_version` and `TargetRubyVersion` (2.5, which may be specified in .rubocop.yml) should be equal.
         end
       RUBY
     end
@@ -76,7 +76,7 @@
       expect_offense(<<~RUBY, '/path/to/bar.gemspec')
         Gem::Specification.new do |spec|
           spec.required_ruby_version = '~> 2.6.0'
-                                       ^^^^^^^^^^ `required_ruby_version` (2.6, declared in bar.gemspec) and `TargetRubyVersion` (2.5, which may be specified in .rubocop.yml) should be equal.
+                                       ^^^^^^^^^^ `required_ruby_version` and `TargetRubyVersion` (2.5, which may be specified in .rubocop.yml) should be equal.
         end
       RUBY
     end
@@ -131,7 +131,7 @@
       expect_offense(<<~RUBY, 'bar.gemspec')
         Gem::Specification.new do |spec|
           spec.required_ruby_version = '>= 2'
-                                       ^^^^^^ `required_ruby_version` (2, declared in bar.gemspec) and `TargetRubyVersion` (2.6, which may be specified in .rubocop.yml) should be equal.
+                                       ^^^^^^ `required_ruby_version` and `TargetRubyVersion` (2.6, which may be specified in .rubocop.yml) should be equal.
         end
       RUBY
     end
@@ -141,7 +141,7 @@
       expect_offense(<<~RUBY, 'bar.gemspec')
         Gem::Specification.new do |spec|
           spec.required_ruby_version = '~> 2'
-                                       ^^^^^^ `required_ruby_version` (2, declared in bar.gemspec) and `TargetRubyVersion` (2.6, which may be specified in .rubocop.yml) should be equal.
+                                       ^^^^^^ `required_ruby_version` and `TargetRubyVersion` (2.6, which may be specified in .rubocop.yml) should be equal.
         end
       RUBY
     end
@@ -150,7 +150,25 @@
   it 'registers an offense when `required_ruby_version` is not specified' do
     expect_offense(<<~RUBY, '/path/to/foo.gemspec')
       Gem::Specification.new do |spec|
-      ^ `required_ruby_version` should be specified.
+      ^{} `required_ruby_version` should be specified.
+      end
+    RUBY
+  end
+
+  it 'registers an offense when `required_ruby_version` is blank' do
+    expect_offense(<<~RUBY, 'bar.gemspec')
+      Gem::Specification.new do |spec|
+        spec.required_ruby_version = ''
+                                     ^^ `required_ruby_version` and `TargetRubyVersion` (2.5, which may be specified in .rubocop.yml) should be equal.
+      end
+    RUBY
+  end
+
+  it 'registers an offense when `required_ruby_version` is an empty array' do
+    expect_offense(<<~RUBY, 'bar.gemspec')
+      Gem::Specification.new do |spec|
+        spec.required_ruby_version = []
+                                     ^^ `required_ruby_version` and `TargetRubyVersion` (2.5, which may be specified in .rubocop.yml) should be equal.
       end
     RUBY
   end