Merge pull request #892 from mbj/fix/argument-mutation

Fix argument mutation by option parser to leak to the outside

Author: mbj

lib/mutant/cli.rb

@@ -80,7 +80,7 @@ def parse(arguments)
         end
       end
 
-      parse_match_expressions(opts.parse!(arguments))
+      parse_match_expressions(opts.parse!(arguments.dup))
 
       config
     end

spec/unit/mutant/cli_spec.rb

@@ -142,11 +142,11 @@ def apply
       allow(kernel).to receive_messages(exit: nil)
     end
 
-    let(:arguments)               { options + expressions     }
-    let(:expected_integration)    { Mutant::Integration::Null }
-    let(:expected_matcher_config) { default_matcher_config    }
-    let(:expressions)             { %w[TestApp*]              }
-    let(:options)                 { []                        }
+    let(:arguments)               { (options + expressions).freeze }
+    let(:expected_integration)    { Mutant::Integration::Null      }
+    let(:expected_matcher_config) { default_matcher_config         }
+    let(:expressions)             { %w[TestApp*]                   }
+    let(:options)                 { []                             }
 
     let(:default_matcher_config) do
       Mutant::Matcher::Config::DEFAULT