Register offenses for variables against regexes in `Performance/Strin…

…gInclude`

changelog/change_register_offenses_for_variables_against.md

@@ -0,0 +1 @@
+* [#332](https://github.com/rubocop/rubocop-performance/pull/332): Register offenses for variables against regexes in `Performance/StringInclude`. ([@fatkodima][])

lib/rubocop/cop/performance/string_include.rb

@@ -6,19 +6,19 @@ module Performance
       # Identifies unnecessary use of a regex where `String#include?` would suffice.
       #
       # @safety
-      #   This cop's offenses are not safe to autocorrect if a receiver is nil.
+      #   This cop's offenses are not safe to autocorrect if a receiver is nil or a Symbol.
       #
       # @example
       #   # bad
-      #   'abc'.match?(/ab/)
-      #   /ab/.match?('abc')
-      #   'abc' =~ /ab/
-      #   /ab/ =~ 'abc'
-      #   'abc'.match(/ab/)
-      #   /ab/.match('abc')
+      #   str.match?(/ab/)
+      #   /ab/.match?(str)
+      #   str =~ /ab/
+      #   /ab/ =~ str
+      #   str.match(/ab/)
+      #   /ab/.match(str)
       #
       #   # good
-      #   'abc'.include?('ab')
+      #   str.include?('ab')
       class StringInclude < Base
         extend AutoCorrector
 
@@ -27,7 +27,7 @@ class StringInclude < Base
 
         def_node_matcher :redundant_regex?, <<~PATTERN
           {(send $!nil? {:match :=~ :!~ :match?} (regexp (str $#literal?) (regopt)))
-           (send (regexp (str $#literal?) (regopt)) {:match :match?} $str)
+           (send (regexp (str $#literal?) (regopt)) {:match :match?} $_)
            (match-with-lvasgn (regexp (str $#literal?) (regopt)) $_)}
         PATTERN
 

spec/rubocop/cop/performance/string_include_spec.rb

@@ -151,11 +151,11 @@
     expect_no_offenses('expect(subject.spin).to match(/\A\n/)')
   end
 
-  # Symbol object does not have `include?` method.
-  # A variable possible to be a symbol object, so if `match?` argument is
-  # a variable, accept it.
-  it 'allows argument of `match?` is not a string literal' do
-    expect_no_offenses('/ /.match?(content_as_symbol)')
+  it 'registers an offense and corrects when argument of `match?` is not a string literal' do
+    expect_offense(<<~RUBY)
+      / /.match?(content)
+      ^^^^^^^^^^^^^^^^^^^ Use `String#include?` instead of a regex match with literal-only pattern.
+    RUBY
   end
 
   it 'registers an offense and corrects when using `!~`' do