Prevent the test framework from being loaded in production mode

The test framework should not be autoloaded in production mode.  Before
this commit, the testing railtie would extend AS::TestCase.  This caused
AS::TestCase to be preloaded regardless of the environment in which we
were running.

This commit just moves the code that adds line filtering support in to
the test command where we actually execute the test runner.  That allows
us to maintain the line runner feature but only load the minimal amount
of code we need.

3 files changed, 14 insertions, 6 deletions

diff --git a/railties/lib/rails/commands/test/test_command.rb b/railties/lib/rails/commands/test/test_command.rb
index 1b2e3af9cc..e97b9cbbba 100644
--- a/railties/lib/rails/commands/test/test_command.rb
+++ b/railties/lib/rails/commands/test/test_command.rb
@@ -1,5 +1,6 @@
 require "rails/command"
 require "rails/test_unit/minitest_plugin"
+require "rails/test_unit/line_filtering"
 
 module Rails
   module Command
@@ -11,6 +12,10 @@ module Rails
       def perform(*)
         $LOAD_PATH << Rails::Command.root.join("test")
 
+        # Add test line filtering support for running test by line number
+        # via the command line.
+        ActiveSupport::TestCase.extend Rails::LineFiltering
+
         Minitest.run_via[:rails] = true
 
         require "active_support/testing/autorun"
diff --git a/railties/lib/rails/test_unit/railtie.rb b/railties/lib/rails/test_unit/railtie.rb
index d0fc795515..ec91673e40 100644
--- a/railties/lib/rails/test_unit/railtie.rb
+++ b/railties/lib/rails/test_unit/railtie.rb
@@ -1,5 +1,3 @@
-require "rails/test_unit/line_filtering"
-
 if defined?(Rake.application) && Rake.application.top_level_tasks.grep(/^(default$|test(:|$))/).any?
   ENV["RAILS_ENV"] ||= "test"
 end
@@ -13,10 +11,6 @@ module Rails
       c.integration_tool :test_unit
     end
 
-    initializer "test_unit.line_filtering" do
-      ActiveSupport::TestCase.extend Rails::LineFiltering
-    end
-
     rake_tasks do
       load "rails/test_unit/testing.rake"
     end
diff --git a/railties/test/application/runner_test.rb b/railties/test/application/runner_test.rb
index 77e7a2cca5..8769703f66 100644
--- a/railties/test/application/runner_test.rb
+++ b/railties/test/application/runner_test.rb
@@ -43,6 +43,15 @@ module ApplicationTests
       assert_match "42", Dir.chdir(app_path) { `bin/rails runner "bin/count_users.rb"` }
     end
 
+    def test_no_minitest_loaded_in_production_mode
+      app_file "bin/print_features.rb", <<-SCRIPT
+      p $LOADED_FEATURES.grep(/minitest/)
+      SCRIPT
+      assert_match "[]", Dir.chdir(app_path) {
+        `RAILS_ENV=production bin/rails runner "bin/print_features.rb"`
+      }
+    end
+
     def test_should_set_dollar_0_to_file
       app_file "bin/dollar0.rb", <<-SCRIPT
       puts $0