Add 'reproduction-order' flag for printing spec order in summary

lib/rspec/core/configuration.rb

@@ -326,6 +326,10 @@ def exclude_pattern=(value)
       # @return [Symbol]
       add_setting :default_color
 
+      # @macro add_setting
+      # Prints the reproduction order of the specs (default: `false`).
+      add_setting :reproduction_order
+
       # @macro add_setting
       # Color used when a pending example is fixed. Defaults to `:blue` but can
       # be set to one of the following: `[:black, :white, :red, :green,
@@ -519,6 +523,7 @@ def initialize
         @fixed_color = :blue
         @detail_color = :cyan
         @profile_examples = false
+        @reproduction_order = false
         @requires = []
         @libs = []
         @derived_metadata_blocks = FilterableItemRepository::QueryOptimized.new(:any?)

lib/rspec/core/notifications.rb

@@ -297,7 +297,8 @@ def fully_formatted
     #                                                  the spec suite
     SummaryNotification = Struct.new(:duration, :examples, :failed_examples,
                                      :pending_examples, :load_time,
-                                     :errors_outside_of_examples_count)
+                                     :errors_outside_of_examples_count,
+                                     :reproduction_order)
     class SummaryNotification
       # @api
       # @return [Fixnum] the number of examples run
@@ -386,6 +387,11 @@ def fully_formatted(colorizer=::RSpec::Core::Formatters::ConsoleCodes)
                     "(files took #{formatted_load_time} to load)\n" \
                     "#{colorized_totals_line(colorizer)}\n"
 
+        if reproduction_order
+          formatted << "\nReproduce this spec order with:\n" \
+                       "rspec --seed ordered #{examples.map(&:location).join(' ')}\n"
+        end
+
         unless failed_examples.empty?
           formatted += (colorized_rerun_commands(colorizer) + "\n")
         end

lib/rspec/core/option_parser.rb

@@ -129,6 +129,10 @@ def parser(options)
           options[:deprecation_stream] = file
         end
 
+        parser.on('--reproduction-order', 'Print the order the specs ran in at the example level') do |_o|
+          options[:reproduction_order] = true
+        end
+
         parser.on('-b', '--backtrace', 'Enable full backtrace.') do |_o|
           options[:full_backtrace] = true
         end

lib/rspec/core/reporter.rb

@@ -176,7 +176,8 @@ def finish
         end
         notify :dump_summary, Notifications::SummaryNotification.new(@duration, @examples, @failed_examples,
                                                                      @pending_examples, @load_time,
-                                                                     @non_example_exception_count)
+                                                                     @non_example_exception_count,
+                                                                     @configuration.reproduction_order)
         notify :seed, Notifications::SeedNotification.new(@configuration.seed, seed_used?)
       end
     end