Add expected rspec duration

spec/support/rspec_run_time.rb

@@ -14,25 +14,72 @@ class RSpecFormatter < RSpec::Core::Formatters::BaseFormatter
       def start(_notification)
         @group_level = 0
         @rspec_test_suite_start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
-        output.puts "\n# Starting RSpec timer..."
+        output.puts "\n# [RSpecRunTime] Starting RSpec timer..."
+
+        init_expected_duration_report
       end
 
-      def example_group_started(_notification)
-        @start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC) if @group_level == 0
+      def example_group_started(notification)
+        if @group_level == 0
+          @current_group_start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+          file_path = spec_file_path(notification)
+          output.puts "# [RSpecRunTime] Starting example group #{file_path}. #{expected_run_time(file_path)}"
+        end
+
         @group_level += 1
       end
 
       def example_group_finished(notification)
         @group_level -= 1 if @group_level > 0
-        return unless @group_level == 0
 
+        if @group_level == 0
+          file_path = spec_file_path(notification)
+          time_now = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+          actual_duration = time_now - @current_group_start_time
+
+          output.puts "\n# [RSpecRunTime] #{file_path} took #{readable_duration(actual_duration)}. " \
+                      "#{expected_run_time(file_path)}"
+        end
+
+        output_elapsed_time
+      end
+
+      private
+
+      def expected_duration_report
+        report_path = ENV['KNAPSACK_RSPEC_SUITE_REPORT_PATH']
+
+        return unless report_path && File.exist?(report_path)
+
+        # rubocop:disable Gitlab/Json -- regular JSON is sufficient
+        @expected_duration_report ||= JSON.parse(File.read(report_path))
+        # rubocop:enable Gitlab/Json
+      end
+      alias_method :init_expected_duration_report, :expected_duration_report
+
+      def spec_file_path(notification)
+        notification.group.metadata[:file_path].sub('./', '')
+      end
+
+      def expected_run_time(spec_file_path)
+        return '' unless expected_duration_report
+
+        expected_duration = expected_duration_report[spec_file_path]
+        return "Missing expected duration from Knapsack report for #{spec_file_path}." unless expected_duration
+
+        "Expected to take #{readable_duration(expected_duration)}."
+      end
+
+      def output_elapsed_time
         time_now = Process.clock_gettime(Process::CLOCK_MONOTONIC)
-        duration = time_now - @start_time
-        elapsed_time = time_now - @rspec_test_suite_start_time
+        elapsed_seconds = time_now - @rspec_test_suite_start_time
+
+        # skip the output unless the duration increased by at least 1 second
+        unless @last_elapsed_seconds.nil? || elapsed_seconds - @last_elapsed_seconds < 1
+          output.puts "# [RSpecRunTime] RSpec elapsed time: #{readable_duration(elapsed_seconds)}.\n\n"
+        end
 
-        output.puts "\n# Example group #{notification.group.description} " \
-                    "(#{notification.group.metadata[:file_path]}) took #{readable_duration(duration)}."
-        output.puts "# RSpec elapsed time: #{readable_duration(elapsed_time)}.\n\n"
+        @last_elapsed_seconds = elapsed_seconds
       end
     end
   end