Load exception presentation sub-system lazily

Author: yujinakayama

lib/rspec/core/formatters.rb

@@ -73,6 +73,7 @@ module RSpec::Core::Formatters
   autoload :ProfileFormatter,         'rspec/core/formatters/profile_formatter'
   autoload :JsonFormatter,            'rspec/core/formatters/json_formatter'
   autoload :BisectFormatter,          'rspec/core/formatters/bisect_formatter'
+  autoload :ExceptionPresenter,       'rspec/core/formatters/exception_presenter'
 
   # Register the formatter class
   # @param formatter_class [Class] formatter class to register

lib/rspec/core/formatters/exception_presenter.rb

@@ -1,4 +1,5 @@
 # encoding: utf-8
+RSpec::Support.require_rspec_core "formatters/snippet_extractor"
 RSpec::Support.require_rspec_support "encoded_string"
 
 module RSpec
@@ -203,7 +204,6 @@ def read_failed_lines
 
           file_path, line_number = matching_line.match(/(.+?):(\d+)(|:\d+)/)[1..2]
           max_line_count = RSpec.configuration.max_displayed_failure_line_count
-          RSpec::Support.require_rspec_core "formatters/snippet_extractor"
           SnippetExtractor.extract_expression_lines_at(file_path, line_number.to_i, max_line_count)
         rescue SnippetExtractor::NoSuchFileError
           ["Unable to find #{file_path} to read failed line"]

spec/rspec/core/formatters/exception_presenter_spec.rb

@@ -404,11 +404,6 @@ def read_failed_lines
       context "when backtrace will generate a security error" do
         let(:exception) { instance_double(Exception, :backtrace => [ "#{__FILE__}:#{__LINE__}"]) }
 
-        before do
-          # We lazily require SnippetExtractor but requiring it in $SAFE 3 environment raises error.
-          RSpec::Support.require_rspec_core "formatters/snippet_extractor"
-        end
-
         it "is handled gracefully" do
           with_safe_set_to_level_that_triggers_security_errors do
             expect { read_failed_lines }.not_to raise_error