Fix offences of the Style/FrozenStringLiteralComment cop

Fixes #1824 (Enabling `# frozen_string_literal: true` in `~/.pryc` crashes most
operations)

23 files changed, 76 insertions, 72 deletions

diff --git a/lib/pry/code.rb b/lib/pry/code.rb
index dcd33d4a..ad38b4f2 100644
--- a/lib/pry/code.rb
+++ b/lib/pry/code.rb
@@ -256,12 +256,12 @@ class Pry
     # @return [String] a formatted representation (based on the configuration of
     #   the object).
     def to_s
-      print_to_output("", false)
+      print_to_output(''.dup, false)
     end
 
     # @return [String] a (possibly highlighted) copy of the source code.
     def highlighted
-      print_to_output("", true)
+      print_to_output(''.dup, true)
     end
 
     # Writes a formatted representation (based on the configuration of the
diff --git a/lib/pry/command.rb b/lib/pry/command.rb
index 6b274133..99bde110 100644
--- a/lib/pry/command.rb
+++ b/lib/pry/command.rb
@@ -354,7 +354,7 @@ class Pry
     # @param [String] val The line of input
     # @return [Array]
     def tokenize(val)
-      val.replace(interpolate_string(val)) if command_options[:interpolate]
+      val = interpolate_string(val) if command_options[:interpolate]
 
       self.class.command_regex =~ val
 
diff --git a/lib/pry/commands/cat/input_expression_formatter.rb b/lib/pry/commands/cat/input_expression_formatter.rb
index 4d8468fe..2f491406 100644
--- a/lib/pry/commands/cat/input_expression_formatter.rb
+++ b/lib/pry/commands/cat/input_expression_formatter.rb
@@ -16,10 +16,10 @@ class Pry
           raise CommandError, "No input expressions!" if numbered_input_items.empty?
 
           if numbered_input_items.length > 1
-            content = ""
+            content = ''
             numbered_input_items.each do |i, s|
-              content << "#{Helpers::Text.bold(i.to_s)}:\n"
-              content << decorate(Pry::Code(s).with_indentation(2)).to_s
+              content += "#{Helpers::Text.bold(i.to_s)}:\n"
+              content += decorate(Pry::Code(s).with_indentation(2)).to_s
             end
 
             content
diff --git a/lib/pry/commands/code_collector.rb b/lib/pry/commands/code_collector.rb
index a827abf6..5ca385f5 100644
--- a/lib/pry/commands/code_collector.rb
+++ b/lib/pry/commands/code_collector.rb
@@ -144,7 +144,7 @@ class Pry
           end
 
           ranged_array = Array(array[range]) || []
-          ranged_array.compact.each { |v| all << yield(v) }
+          ranged_array.compact.each { |v| all += yield(v) }
         end
 
         all
diff --git a/lib/pry/commands/edit.rb b/lib/pry/commands/edit.rb
index 1819f8a4..4c31e089 100644
--- a/lib/pry/commands/edit.rb
+++ b/lib/pry/commands/edit.rb
@@ -71,9 +71,7 @@ class Pry
           initial_temp_file_content,
           initial_temp_file_content.lines.count
         )
-        silence_warnings do
-          eval_string.replace content
-        end
+        pry_instance.eval_string = content
         Pry.history.push(content)
       end
 
diff --git a/lib/pry/commands/find_method.rb b/lib/pry/commands/find_method.rb
index 31a6a319..6afced3c 100644
--- a/lib/pry/commands/find_method.rb
+++ b/lib/pry/commands/find_method.rb
@@ -99,7 +99,7 @@ class Pry
       # if `-c` was not given
       def additional_info(header, method)
         if opts.content?
-          ": " << colorize_code(matched_method_lines(header, method))
+          ': ' + colorize_code(matched_method_lines(header, method))
         else
           ""
         end
diff --git a/lib/pry/commands/fix_indent.rb b/lib/pry/commands/fix_indent.rb
index 6c338691..4974acb4 100644
--- a/lib/pry/commands/fix_indent.rb
+++ b/lib/pry/commands/fix_indent.rb
@@ -14,7 +14,7 @@ class Pry
 
       def process
         indented_str = Pry::Indent.indent(eval_string)
-        eval_string.replace indented_str
+        pry_instance.eval_string = indented_str
       end
     end
 
diff --git a/lib/pry/commands/help.rb b/lib/pry/commands/help.rb
index 03f82895..1dee2c64 100644
--- a/lib/pry/commands/help.rb
+++ b/lib/pry/commands/help.rb
@@ -60,7 +60,7 @@ class Pry
       # @param [Array<Pry::Command>] commands
       # @return [String] The generated help string.
       def help_text_for_commands(name, commands)
-        "#{bold(name.capitalize)}\n" << commands.map do |command|
+        "#{bold(name.capitalize)}\n" + commands.map do |command|
           "  #{command.options[:listing].to_s.ljust(18)} " \
           "#{command.description.capitalize}"
         end.join("\n")
diff --git a/lib/pry/commands/ls/formatter.rb b/lib/pry/commands/ls/formatter.rb
index c5163ca5..ddd17842 100644
--- a/lib/pry/commands/ls/formatter.rb
+++ b/lib/pry/commands/ls/formatter.rb
@@ -35,7 +35,7 @@ class Pry
         end
 
         def format_value(value)
-          Pry::ColorPrinter.pp(value, '')
+          Pry::ColorPrinter.pp(value, ''.dup)
         end
 
         def correct_opts?
diff --git a/lib/pry/commands/show_info.rb b/lib/pry/commands/show_info.rb
index 4e982af8..9037cc1f 100644
--- a/lib/pry/commands/show_info.rb
+++ b/lib/pry/commands/show_info.rb
@@ -75,7 +75,7 @@ class Pry
       end
 
       def content_and_header_for_code_object(code_object)
-        header(code_object) << content_for(code_object)
+        header(code_object) + content_for(code_object)
       end
 
       def content_and_headers_for_all_module_candidates(mod)
@@ -84,13 +84,13 @@ class Pry
         mod.number_of_candidates.times do |v|
           candidate = mod.candidate(v)
           begin
-            result << "\nCandidate #{v + 1}/#{mod.number_of_candidates}: " \
+            result += "\nCandidate #{v + 1}/#{mod.number_of_candidates}: " \
                       "#{candidate.source_file}:#{candidate.source_line}\n"
             content = content_for(candidate)
 
-            result << "Number of lines: #{content.lines.count}\n\n" << content
+            result += "Number of lines: #{content.lines.count}\n\n" + content
           rescue Pry::RescuableException
-            result << "\nNo content found.\n"
+            result += "\nNo content found.\n"
             next
           end
         end
@@ -108,17 +108,17 @@ class Pry
         content = content_for(code_object)
 
         h = "\n#{bold('From:')} #{file_name}"
-        h << code_object_header(code_object, line_num)
-        h << "\n#{bold('Number of lines:')} " << "#{content.lines.count}\n\n"
+        h += code_object_header(code_object, line_num)
+        h += "\n#{bold('Number of lines:')} " + "#{content.lines.count}\n\n"
         if @used_super
-          h << bold('** Warning:')
-          h << " Cannot find code for #{@original_code_object.nonblank_name}. " \
+          h += bold('** Warning:')
+          h += " Cannot find code for #{@original_code_object.nonblank_name}. " \
                "Showing superclass #{code_object.nonblank_name} instead. **\n\n"
         end
 
         if content.lines.none?
-          h << bold('** Warning:')
-          h << " Cannot find code for '#{code_object.name}' (source_location is nil)"
+          h += bold('** Warning:')
+          h += " Cannot find code for '#{code_object.name}' (source_location is nil)"
         end
 
         h
@@ -141,23 +141,23 @@ class Pry
 
       def method_header(code_object, line_num)
         h = ""
-        h << (code_object.c_method? ? ' (C Method):' : ":#{line_num}:")
-        h << method_sections(code_object)[:owner]
-        h << method_sections(code_object)[:visibility]
-        h << method_sections(code_object)[:signature]
+        h += (code_object.c_method? ? ' (C Method):' : ":#{line_num}:")
+        h += method_sections(code_object)[:owner]
+        h += method_sections(code_object)[:visibility]
+        h += method_sections(code_object)[:signature]
         h
       end
 
       def module_header(code_object, line_num)
         h = ""
-        h << ":#{line_num}\n"
-        h << bold(code_object.module? ? "Module" : "Class")
-        h << " #{bold('name:')} #{code_object.nonblank_name}"
+        h += ":#{line_num}\n"
+        h += bold(code_object.module? ? "Module" : "Class")
+        h += " #{bold('name:')} #{code_object.nonblank_name}"
 
         if code_object.number_of_candidates > 1
-          h << bold("\nNumber of monkeypatches: ")
-          h << code_object.number_of_candidates.to_s
-          h << ". Use the `-a` option to display all available monkeypatches"
+          h += bold("\nNumber of monkeypatches: ")
+          h += code_object.number_of_candidates.to_s
+          h += ". Use the `-a` option to display all available monkeypatches"
         end
         h
       end
diff --git a/lib/pry/commands/watch_expression/expression.rb b/lib/pry/commands/watch_expression/expression.rb
index 3b0d605a..2214b875 100644
--- a/lib/pry/commands/watch_expression/expression.rb
+++ b/lib/pry/commands/watch_expression/expression.rb
@@ -14,7 +14,7 @@ class Pry
 
         def eval!
           @previous_value = value
-          @value = Pry::ColorPrinter.pp(target_eval(target, source), "")
+          @value = Pry::ColorPrinter.pp(target_eval(target, source), ''.dup)
         end
 
         def to_s
diff --git a/lib/pry/commands/whereami.rb b/lib/pry/commands/whereami.rb
index 5adc187a..f18026e4 100644
--- a/lib/pry/commands/whereami.rb
+++ b/lib/pry/commands/whereami.rb
@@ -107,7 +107,7 @@ class Pry
           .with_marker(marker)
           .highlighted
         pry_instance.pager.page(
-          "\n#{bold('From:')} #{location}:\n\n" << pretty_code << "\n"
+          "\n#{bold('From:')} #{location}:\n\n" + pretty_code + "\n"
         )
       end
 
diff --git a/lib/pry/input_completer.rb b/lib/pry/input_completer.rb
index 16d55fb1..9566b32d 100644
--- a/lib/pry/input_completer.rb
+++ b/lib/pry/input_completer.rb
@@ -94,7 +94,7 @@ class Pry
         when SYMBOL_REGEXP # Symbol
           if Symbol.respond_to?(:all_symbols)
             sym = Regexp.quote(Regexp.last_match(1))
-            candidates = Symbol.all_symbols.collect { |s| ":" << s.id2name }
+            candidates = Symbol.all_symbols.collect { |s| ":" + s.id2name }
             candidates.grep(/^#{sym}/)
           else
             []
@@ -102,7 +102,7 @@ class Pry
         when TOPLEVEL_LOOKUP_REGEXP # Absolute Constant or class methods
           receiver = Regexp.last_match(1)
           candidates = Object.constants.collect(&:to_s)
-          candidates.grep(/^#{receiver}/).collect { |e| "::" << e }
+          candidates.grep(/^#{receiver}/).collect { |e| "::" + e }
         when CONSTANT_REGEXP # Constant
           message = Regexp.last_match(1)
           begin
@@ -230,7 +230,7 @@ class Pry
       candidates.grep(/^#{message}/).collect do |e|
         next unless e =~ /^[a-zA-Z_]/
 
-        path.call(receiver + "." << e)
+        path.call(receiver + "." + e)
       end.compact
     end
 
diff --git a/lib/pry/object_path.rb b/lib/pry/object_path.rb
index b200c2bb..28895a34 100644
--- a/lib/pry/object_path.rb
+++ b/lib/pry/object_path.rb
@@ -37,13 +37,13 @@ class Pry
 
           loop do
             # Scan for as long as we don't see a slash
-            next_segment << scanner.scan(%r{[^/]*})
+            next_segment += scanner.scan(%r{[^/]*})
 
             if complete?(next_segment) || scanner.eos?
               scanner.getch # consume the slash
               break
             else
-              next_segment << scanner.getch # append the slash
+              next_segment += scanner.getch # append the slash
             end
           end
 
diff --git a/lib/pry/pager.rb b/lib/pry/pager.rb
index 966e06c1..693e9e8e 100644
--- a/lib/pry/pager.rb
+++ b/lib/pry/pager.rb
@@ -170,7 +170,7 @@ class Pry
           write_to_pager str
         else
           @tracker.record str
-          @buffer << str
+          @buffer += str
 
           write_to_pager @buffer if @tracker.page?
         end
diff --git a/lib/pry/pry_instance.rb b/lib/pry/pry_instance.rb
index b46e703d..ef963a07 100644
--- a/lib/pry/pry_instance.rb
+++ b/lib/pry/pry_instance.rb
@@ -81,7 +81,7 @@ class Pry
   def initialize(options = {})
     @binding_stack = []
     @indent        = Pry::Indent.new
-    @eval_string   = ""
+    @eval_string   = ''.dup
     @backtrace     = options.delete(:backtrace) || caller
     target = options.delete(:target)
     @config = self.class.config.merge(options)
@@ -229,7 +229,7 @@ class Pry
   # Reset the current eval string. If the user has entered part of a multiline
   # expression, this discards that input.
   def reset_eval_string
-    @eval_string = ""
+    @eval_string = ''.dup
   end
 
   # Pass a line of input to Pry.
@@ -345,7 +345,7 @@ class Pry
         # the command that was invoked was non-void (had a return value) and so we make
         # the value of the current expression equal to the return value
         # of the command.
-        @eval_string.replace "::Pry.current[:pry_cmd_result].retval\n"
+        @eval_string = "::Pry.current[:pry_cmd_result].retval\n"
       end
       true
     else
@@ -608,7 +608,7 @@ class Pry
     inject_sticky_locals!
     begin
       unless process_command_safely(line)
-        @eval_string << "#{line.chomp}\n" if !line.empty? || !@eval_string.empty?
+        @eval_string += "#{line.chomp}\n" if !line.empty? || !@eval_string.empty?
       end
     rescue RescuableException => e
       self.last_exception = e
diff --git a/lib/pry/slop/option.rb b/lib/pry/slop/option.rb
index 8a0df7e1..d39998b8 100644
--- a/lib/pry/slop/option.rb
+++ b/lib/pry/slop/option.rb
@@ -127,12 +127,12 @@ class Pry
         out = "    #{short ? "-#{short}, " : ' ' * 4}"
 
         if long
-          out << "--#{long}"
+          out += "--#{long}"
           size = long.size
           diff = @slop.config[:longest_flag] - size
-          out << (' ' * (diff + 6))
+          out += (' ' * (diff + 6))
         else
-          out << (' ' * (@slop.config[:longest_flag] + 8))
+          out += (' ' * (@slop.config[:longest_flag] + 8))
         end
 
         "#{out}#{description}"
diff --git a/spec/command_integration_spec.rb b/spec/command_integration_spec.rb
index c1b63052..7579da62 100644
--- a/spec/command_integration_spec.rb
+++ b/spec/command_integration_spec.rb
@@ -452,7 +452,6 @@ describe "commands" do
   ) do
     klass = Pry::CommandSet.new do
       command "hello", "", keep_retval: true do
-        eval_string.replace("6")
         7
       end
     end
diff --git a/spec/commands/play_spec.rb b/spec/commands/play_spec.rb
index 000f6fe5..04573eb9 100644
--- a/spec/commands/play_spec.rb
+++ b/spec/commands/play_spec.rb
@@ -37,6 +37,7 @@ describe "play" do
     it 'should play a file' do
       @t.process_command 'play spec/fixtures/whereami_helper.rb'
       expect(@t.eval_string).to eq unindent(<<-STR)
+        # frozen_string_literal: true
         # rubocop:disable Layout/EmptyLineBetweenDefs
         class Cor
           def a; end
@@ -50,16 +51,18 @@ describe "play" do
 
     it 'should output file contents with print option' do
       @t.process_command 'play --print spec/fixtures/whereami_helper.rb'
-      expect(@t.last_output).to eq unindent(<<-STR)
-        1: # rubocop:disable Layout/EmptyLineBetweenDefs
-        2: class Cor
-        3:   def a; end
-        4:   def b; end
-        5:   def c; end
-        6:   def d; end
-        7: end
-        8: # rubocop:enable Layout/EmptyLineBetweenDefs
-      STR
+      expect(@t.last_output).to eq(
+        " 1: \# frozen_string_literal: true\n" \
+        " 2: \n" \
+        " 3: \# rubocop:disable Layout/EmptyLineBetweenDefs\n" \
+        " 4: class Cor\n" \
+        " 5:   def a; end\n" \
+        " 6:   def b; end\n" \
+        " 7:   def c; end\n" \
+        " 8:   def d; end\n" \
+        " 9: end\n" \
+        "10: \# rubocop:enable Layout/EmptyLineBetweenDefs\n"
+      )
     end
   end
 
diff --git a/spec/helpers/table_spec.rb b/spec/helpers/table_spec.rb
index 66b3acfa..aad9ed6b 100644
--- a/spec/helpers/table_spec.rb
+++ b/spec/helpers/table_spec.rb
@@ -22,7 +22,8 @@ describe 'Formatting Table' do
     def try_round_trip(expected)
       things = expected.split(/\s+/).sort
       actual = Pry::Helpers.tablify(things, FAKE_COLUMNS).to_s.strip
-      [expected, actual].each { |e| e.gsub!(/\s+$/, '') }
+      expected = expected.gsub(/\s+$/, '')
+      actual = actual.gsub(/\s+$/, '')
       if actual != expected
         bar = '-' * 25
         puts \
diff --git a/spec/hooks_spec.rb b/spec/hooks_spec.rb
index 0b8d6f9c..16af79a4 100644
--- a/spec/hooks_spec.rb
+++ b/spec/hooks_spec.rb
@@ -123,14 +123,14 @@ describe Pry::Hooks do
       end
 
       it 'should preserve hook order' do
-        name = ""
+        name = ''
         h1 = Pry::Hooks.new
-        h1.add_hook(:test_hook, :testing3) { name << "h" }
-        h1.add_hook(:test_hook, :testing4) { name << "n" }
+        h1.add_hook(:test_hook, :testing3) { name += "h" }
+        h1.add_hook(:test_hook, :testing4) { name += "n" }
 
         h2 = Pry::Hooks.new
-        h2.add_hook(:test_hook, :testing1) { name << "j" }
-        h2.add_hook(:test_hook, :testing2) { name << "o" }
+        h2.add_hook(:test_hook, :testing1) { name += "j" }
+        h2.add_hook(:test_hook, :testing2) { name += "o" }
 
         h2.merge!(h1)
         h2.exec_hook(:test_hook)
diff --git a/spec/pryrc_spec.rb b/spec/pryrc_spec.rb
index a7b5fc2a..59f2eed9 100644
--- a/spec/pryrc_spec.rb
+++ b/spec/pryrc_spec.rb
@@ -39,7 +39,7 @@ describe Pry do
     it "should not load the pryrc if pryrc's directory permissions do not allow this" do
       Dir.mktmpdir do |dir|
         File.chmod 0o000, dir
-        Pry::LOCAL_RC_FILE.replace File.join(dir, '.pryrc')
+        stub_const('Pry::LOCAL_RC_FILE', File.join(dir, '.pryrc'))
         Pry.config.should_load_rc = true
         expect do
           Pry.start(self, input: StringIO.new("exit-all\n"), output: StringIO.new)
diff --git a/spec/wrapped_module_spec.rb b/spec/wrapped_module_spec.rb
index a97affb9..138b9b1a 100644
--- a/spec/wrapped_module_spec.rb
+++ b/spec/wrapped_module_spec.rb
@@ -185,7 +185,8 @@ describe Pry::WrappedModule do
 
   describe ".singleton_class?" do
     it "should be true for singleton classes" do
-      expect(Pry::WrappedModule.new(class << ""; self; end).singleton_class?).to eq true
+      mod = Pry::WrappedModule.new(class << Object.new; self; end)
+      expect(mod).to be_singleton_class
     end
 
     it "should be false for normal classes" do
@@ -204,10 +205,12 @@ describe Pry::WrappedModule do
     end
 
     it "should return the attached object" do
-      expect(Pry::WrappedModule.new(class << "hi"; self; end).singleton_instance)
-        .to eq "hi"
-      expect(Pry::WrappedModule.new(class << Object; self; end).singleton_instance)
-        .to equal(Object)
+      instance = Object.new
+      mod = class << instance; self; end
+      expect(Pry::WrappedModule.new(mod).singleton_instance).to eq(instance)
+
+      klass = class << Object; self; end
+      expect(Pry::WrappedModule.new(klass).singleton_instance).to equal(Object)
     end
   end