Eliminate dependency on Rails::VERSION::STRING

To facilitate the use of ActiveSupport::Testing::Performance outside
of a Rails application conditionally check for the presence of
Rails::VERSION::STRING before including it in the environment string.

activesupport/lib/active_support/testing/performance.rb

 require 'fileutils'
-require 'rails/version'
 require 'active_support/concern'
 require 'active_support/core_ext/class/delegating_attributes'
 require 'active_support/core_ext/string/inflections'
@@ -149,26 +148,20 @@ def record
         end
 
         def environment
-          unless defined? @env
-            app = "#{$1}.#{$2}" if File.directory?('.git') && `git branch -v` =~ /^\* (\S+)\s+(\S+)/
-
-            rails = Rails::VERSION::STRING
-            if File.directory?('vendor/rails/.git')
-              Dir.chdir('vendor/rails') do
-                rails += ".#{$1}.#{$2}" if `git branch -v` =~ /^\* (\S+)\s+(\S+)/
-              end
-            end
-
-            ruby = "#{RUBY_ENGINE}-#{RUBY_VERSION}.#{RUBY_PATCHLEVEL}"
-
-            @env = [app, rails, ruby, RUBY_PLATFORM] * ','
-          end
-
-          @env
+          @env ||= [].tap do |env|
+            env << "#{$1}.#{$2}" if File.directory?('.git') && `git branch -v` =~ /^\* (\S+)\s+(\S+)/
+            env << rails_version if defined?(Rails::VERSION::STRING)
+            env << "#{RUBY_ENGINE}-#{RUBY_VERSION}.#{RUBY_PATCHLEVEL}"
+            env << RUBY_PLATFORM
+          end.join(',')
         end
 
         protected
-          HEADER = 'measurement,created_at,app,rails,ruby,platform'
+          if defined?(Rails::VERSION::STRING)
+            HEADER = 'measurement,created_at,app,rails,ruby,platform'
+          else
+            HEADER = 'measurement,created_at,app,ruby,platform'
+          end
 
           def with_output_file
             fname = output_filename
@@ -186,6 +179,18 @@ def with_output_file
           def output_filename
             "#{super}.csv"
           end
+
+          def rails_version
+            "rails-#{Rails::VERSION::STRING}#{rails_branch}"
+          end
+
+          def rails_branch
+            if File.directory?('vendor/rails/.git')
+              Dir.chdir('vendor/rails') do
+                ".#{$1}.#{$2}" if `git branch -v` =~ /^\* (\S+)\s+(\S+)/
+              end
+            end
+          end
       end
 
       module Metrics

activesupport/test/core_ext/kernel_test.rb

@@ -96,7 +96,6 @@ def test_debugger_not_available_message_to_stderr
   end
 
   def test_debugger_not_available_message_to_rails_logger
-    Object.send(:remove_const, :Rails) if Object.const_defined?(:Rails)
     rails = Class.new do
       def self.logger
         @logger ||= MockStdErr.new

activesupport/test/testing/performance_test.rb

@@ -11,7 +11,7 @@ def test_amount_format
         assert_equal "1", amount_metric.format(1.23)
         assert_equal "40,000,000", amount_metric.format(40000000)
       end
-      
+
       def test_time_format
         time_metric = ActiveSupport::Testing::Performance::Metrics[:time].new
         assert_equal "0 ms", time_metric.format(0)
@@ -21,7 +21,7 @@ def test_time_format
         assert_equal "40000.00 sec", time_metric.format(40000)
         assert_equal "-5000 ms", time_metric.format(-5)
       end
-      
+
       def test_space_format
         space_metric = ActiveSupport::Testing::Performance::Metrics[:digital_information_unit].new
         assert_equal "0 Bytes", space_metric.format(0)
@@ -35,6 +35,25 @@ def test_space_format
         assert_equal "91 TB", space_metric.format(10**14)
         assert_equal "910000 TB", space_metric.format(10**18)
       end
+
+      def test_environment_format_without_rails
+        metric = ActiveSupport::Testing::Performance::Metrics[:time].new
+        benchmarker = ActiveSupport::Testing::Performance::Benchmarker.new(self, metric)
+        assert_equal "#{RUBY_ENGINE}-#{RUBY_VERSION}.#{RUBY_PATCHLEVEL},#{RUBY_PLATFORM}", benchmarker.environment
+      end
+
+      def test_environment_format_with_rails
+        rails, version = Module.new, Module.new
+        version.const_set :STRING, "4.0.0"
+        rails.const_set :VERSION, version
+        Object.const_set :Rails, rails
+
+        metric = ActiveSupport::Testing::Performance::Metrics[:time].new
+        benchmarker = ActiveSupport::Testing::Performance::Benchmarker.new(self, metric)
+        assert_equal "rails-4.0.0,#{RUBY_ENGINE}-#{RUBY_VERSION}.#{RUBY_PATCHLEVEL},#{RUBY_PLATFORM}", benchmarker.environment
+      ensure
+        Object.send :remove_const, :Rails
+      end
     end
   end
 end
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