[Fix #7728] Fix an error for Style/OneLineConditional

Fixes #7728.

This PR fixes an error for `Style/OneLineConditional`
when one of the branches contains a self keyword.

CHANGELOG.md

@@ -30,6 +30,7 @@
 * [#7778](https://github.com/rubocop-hq/rubocop/issues/7778): Fix a false positive for `Layout/EndAlignment` when a non-whitespace is used before the `end` keyword. ([@koic][])
 * [#7806](https://github.com/rubocop-hq/rubocop/pull/7806): Fix an error for `Lint/ErbNewArguments` cop when inspecting `ActionView::Template::Handlers::ERB.new`. ([@koic][])
 * [#7814](https://github.com/rubocop-hq/rubocop/issues/7814): Fix a false positive for `Migrate/DepartmentName` cop when inspecting an unexpected disabled comment format. ([@koic][])
+* [#7728](https://github.com/rubocop-hq/rubocop/issues/7728): Fix an error for `Style/OneLineConditional` when one of the branches contains a self keyword. ([@koic][])
 
 ### Changes
 

lib/rubocop.rb

@@ -59,6 +59,7 @@
 require_relative 'rubocop/ast/node/retry_node'
 require_relative 'rubocop/ast/node/return_node'
 require_relative 'rubocop/ast/node/self_class_node'
+require_relative 'rubocop/ast/node/self_node'
 require_relative 'rubocop/ast/node/send_node'
 require_relative 'rubocop/ast/node/str_node'
 require_relative 'rubocop/ast/node/super_node'

lib/rubocop/ast/builder.rb

@@ -44,6 +44,7 @@ class Builder < Parser::Builders::Default
         resbody:      ResbodyNode,
         retry:        RetryNode,
         return:       ReturnNode,
+        self:         SelfNode,
         csend:        SendNode,
         send:         SendNode,
         str:          StrNode,

lib/rubocop/ast/node/self_node.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module AST
+    # A node extension for `self` nodes. This will be used in place of a
+    # plain node when the builder constructs the AST, making its methods
+    # available to all `self` nodes within RuboCop.
+    class SelfNode < Node
+      include MethodIdentifierPredicates
+
+      # Always return `false` because `self` cannot have arguments.
+      def arguments?
+        false
+      end
+    end
+  end
+end

spec/rubocop/ast/self_node_spec.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::AST::SelfNode do
+  let(:source) { 'self' }
+  let(:self_node) { parse_source(source).ast }
+
+  describe '.new' do
+    it { expect(self_node.is_a?(described_class)).to be(true) }
+  end
+
+  describe '#arguments?' do
+    it { expect(self_node.arguments?).to be(false) }
+  end
+end

spec/rubocop/cop/style/one_line_conditional_spec.rb

@@ -130,4 +130,15 @@
       true ? break : 7
     RUBY
   end
+
+  it 'does not break when one of the branches contains a self keyword' do
+    expect_offense(<<~RUBY)
+      if true then self else 7 end
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Favor the ternary operator (`?:`) over `if/then/else/end` constructs.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      true ? self : 7
+    RUBY
+  end
 end