Skip group options regexp_parser can't parse

lib/mutant/ast/regexp.rb

@@ -15,7 +15,9 @@ def self.parse(regexp)
         ::Regexp::Parser.parse(regexp)
       # `regexp_parser` is more strict than MRI
       # See: https://github.com/ammar/regexp_parser/issues/75
-      rescue ::Regexp::Scanner::PrematureEndError
+      # Also: https://github.com/ammar/regexp_parser/issues/76
+      rescue ::Regexp::Scanner::PrematureEndError,
+             ::Regexp::Scanner::InvalidGroupOption
       end
       # rubocop:enable Lint/SuppressedException
 

meta/regexp.rb

@@ -75,7 +75,8 @@
   mutation '/(?(1)(foo)(?:bar))/'
 end
 
-# Case where MRI would accept an expression but regexp_parser not.
+# MRI accepts this regex but `regexp_parser` does not.
+# See: https://github.com/ammar/regexp_parser/issues/75
 Mutant::Meta::Example.add :regexp do
   source '/\xA/'
 
@@ -84,6 +85,16 @@
   mutation '/nomatch\A/'
 end
 
+# MRI accepts this regex but `regexp_parser` does not.
+# See: https://github.com/ammar/regexp_parser/issues/76
+Mutant::Meta::Example.add :regexp do
+  source '/(?<æ>.)/'
+
+  singleton_mutations
+  mutation '//'
+  mutation '/nomatch\A/'
+end
+
 Pathname
   .glob(Pathname.new(__dir__).join('regexp', '*.rb'))
   .sort

spec/unit/mutant/ast/regexp/parse_spec.rb

@@ -11,9 +11,15 @@ def apply(input)
     end
   end
 
-  context 'on regexp regexp_parser does not accept' do
+  context 'when given a hex escape `regexp_parser` does not support' do
     it 'returns nil' do
       expect(apply(/\xA/)).to be(nil)
     end
   end
+
+  context 'when given a capture group `regexp_parser` does not support' do
+    it 'returns nil' do
+      expect(apply(/(?<æ>.)/)).to be(nil)
+    end
+  end
 end