[Fix rubocop#289] Fix a false positive for `Performance/StringIdentif…

…ierArgument`

Fixes rubocop#289.

This PR fixes a false positive for `Performance/StringIdentifierArgument`
when using namespaced class string argument.

changelog/fix_a_false_positive_for_performance_string_identifier_argument.md

@@ -0,0 +1 @@
+* [#289](https://github.com/rubocop/rubocop-performance/issues/289): Fix a false positive for `Performance/StringIdentifierArgument` when using namespaced class string argument. ([@koic][])

lib/rubocop/cop/performance/string_identifier_argument.rb

@@ -46,7 +46,7 @@ class StringIdentifierArgument < Base
         def on_send(node)
           return unless (first_argument = node.first_argument)
           return unless first_argument.str_type?
-          return if first_argument.value.include?(' ')
+          return if first_argument.value.include?(' ') || first_argument.value.include?('::')
 
           replacement = first_argument.value.to_sym.inspect
 

spec/rubocop/cop/performance/string_identifier_argument_spec.rb

@@ -38,6 +38,18 @@
     RUBY
   end
 
+  it 'does not register an offense when using cbase class string argument' do
+    expect_no_offenses(<<~RUBY)
+      Object.const_defined?('::Foo')
+    RUBY
+  end
+
+  it 'does not register an offense when using namespaced class string argument' do
+    expect_no_offenses(<<~RUBY)
+      Object.const_defined?('Foo::Bar')
+    RUBY
+  end
+
   it 'does not register an offense when using symbol argument for no identifier argument' do
     expect_no_offenses(<<~RUBY)
       foo('do_something')