* Don't eagerly require Rails' minitest plugin.

By making the Rails minitest behave like a standard minitest plugin
we're much more likely to not break when people use other minitest
plugins. Like minitest-focus and pride.

To do this, we need to behave like minitest: require files up front
and then perform the plugin behavior via the at_exit hook.
This also saves us a fair bit of wrangling with test file loading.

Finally, since the environment and warnings options have to be applied
as early as possible, and since minitest loads plugins at_exit, they
have to be moved to the test command.

* Don't expect the root method.

It's likely this worked because we eagerly loaded the Rails minitest plugin
and that somehow defined a root method on `Rails`.

* Assign a backtrace to failed exceptions.

Otherwise Minitest pukes when attempting to filter the backtrace (which
Rails' backtrace cleaner then removes).

Means the exception message test has to be revised too.

This is likely caused by the rails minitest plugin now being loaded for
these tests and assigning a default backtrace cleaner.

15 files changed, 251 insertions, 275 deletions

diff --git a/activerecord/lib/active_record/tasks/database_tasks.rb b/activerecord/lib/active_record/tasks/database_tasks.rb
index ba686fc562..3fbfcc9b47 100644
--- a/activerecord/lib/active_record/tasks/database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/database_tasks.rb
@@ -260,7 +260,7 @@ module ActiveRecord
       def check_schema_file(filename)
         unless File.exist?(filename)
           message = %{#{filename} doesn't exist yet. Run `rails db:migrate` to create it, then try again.}
-          message << %{ If you do not intend to use a database, you should instead alter #{Rails.root}/config/application.rb to limit the frameworks that will be loaded.} if defined?(::Rails)
+          message << %{ If you do not intend to use a database, you should instead alter #{Rails.root}/config/application.rb to limit the frameworks that will be loaded.} if defined?(::Rails.root)
           Kernel.abort message
         end
       end
diff --git a/activesupport/lib/active_support/testing/autorun.rb b/activesupport/lib/active_support/testing/autorun.rb
index 40ae696a34..a4afbfd6ce 100644
--- a/activesupport/lib/active_support/testing/autorun.rb
+++ b/activesupport/lib/active_support/testing/autorun.rb
@@ -3,8 +3,4 @@ gem "minitest"
 
 require "minitest"
 
-if Minitest.respond_to?(:run_via) && !Minitest.run_via.set?
-  Minitest.run_via = :ruby
-end
-
 Minitest.autorun
diff --git a/railties/CHANGELOG.md b/railties/CHANGELOG.md
index d793405da1..761e2f4ded 100644
--- a/railties/CHANGELOG.md
+++ b/railties/CHANGELOG.md
@@ -1,3 +1,11 @@
+*   Make Rails' test runner work better with minitest plugins.
+
+    By demoting the Rails test runner to just another minitest plugin —
+    and thereby not eager loading it — we can co-exist much better with
+    other minitest plugins such as pride and minitest-focus.
+
+    *Kasper Timm Hansen*
+
 *   Load environment file in `dbconsole` command.
 
     Fixes #29717
diff --git a/railties/lib/minitest/rails_plugin.rb b/railties/lib/minitest/rails_plugin.rb
new file mode 100644
index 0000000000..fec9ae64d8
--- /dev/null
+++ b/railties/lib/minitest/rails_plugin.rb
@@ -0,0 +1,49 @@
+require "active_support/core_ext/module/attribute_accessors"
+require "rails/test_unit/reporter"
+
+module Minitest
+  class SuppressedSummaryReporter < SummaryReporter
+    # Disable extra failure output after a run if output is inline.
+    def aggregated_results(*)
+      super unless options[:output_inline]
+    end
+  end
+
+  def self.plugin_rails_options(opts, options)
+    opts.on("-b", "--backtrace", "Show the complete backtrace") do
+      options[:full_backtrace] = true
+    end
+
+    opts.on("-d", "--defer-output", "Output test failures and errors after the test run") do
+      options[:output_inline] = false
+    end
+
+    opts.on("-f", "--fail-fast", "Abort test run on first failure or error") do
+      options[:fail_fast] = true
+    end
+
+    opts.on("-c", "--[no-]color", "Enable color in the output") do |value|
+      options[:color] = value
+    end
+
+    options[:color] = true
+    options[:output_inline] = true
+  end
+
+  # Owes great inspiration to test runner trailblazers like RSpec,
+  # minitest-reporters, maxitest and others.
+  def self.plugin_rails_init(options)
+    unless options[:full_backtrace] || ENV["BACKTRACE"]
+      # Plugin can run without Rails loaded, check before filtering.
+      Minitest.backtrace_filter = ::Rails.backtrace_cleaner if ::Rails.respond_to?(:backtrace_cleaner)
+    end
+
+    # Replace progress reporter for colors.
+    reporter.reporters.delete_if { |reporter| reporter.kind_of?(SummaryReporter) || reporter.kind_of?(ProgressReporter) }
+    reporter << SuppressedSummaryReporter.new(options[:io], options)
+    reporter << ::Rails::TestUnitReporter.new(options[:io], options)
+  end
+
+  # Backwardscompatibility with Rails 5.0 generated plugin test scripts
+  mattr_reader :run_via, default: {}
+end
diff --git a/railties/lib/rails/commands/test/test_command.rb b/railties/lib/rails/commands/test/test_command.rb
index ca0b6c00fe..5852f51a62 100644
--- a/railties/lib/rails/commands/test/test_command.rb
+++ b/railties/lib/rails/commands/test/test_command.rb
@@ -1,21 +1,41 @@
 require_relative "../../command"
-require_relative "../../test_unit/minitest_plugin"
+require_relative "../../test_unit/runner"
 
 module Rails
   module Command
     class TestCommand < Base # :nodoc:
       no_commands do
         def help
-          perform # Hand over help printing to minitest.
+          require "optparse"
+          require "minitest/rails_plugin"
+
+          opts = OptionParser.new
+          opts.banner = "Usage: #{Rails::TestUnitReporter.executable} [options] [files or directories]"
+          opts.separator ""
+          opts.separator "You can run a single test by appending a line number to a filename:"
+          opts.separator ""
+          opts.separator "    #{Rails::TestUnitReporter.executable} test/models/user_test.rb:27"
+          opts.separator ""
+          opts.separator "You can run multiple files and directories at the same time:"
+          opts.separator ""
+          opts.separator "    #{Rails::TestUnitReporter.executable} test/controllers test/integration/login_test.rb"
+          opts.separator ""
+          opts.separator "By default test failures and errors are reported inline during a run."
+          opts.separator ""
+
+          opts.separator "Rails options:"
+          Rails::TestUnit::Runner.options(opts)
+          Minitest.plugin_rails_options(opts, {})
+
+          say opts
         end
       end
 
       def perform(*)
         $LOAD_PATH << Rails::Command.root.join("test").to_s
 
-        Minitest.run_via = :rails
-
-        require "active_support/testing/autorun"
+        Rails::TestUnit::Runner.parse_options(ARGV)
+        Rails::TestUnit::Runner.run(ARGV)
       end
     end
   end
diff --git a/railties/lib/rails/plugin/test.rb b/railties/lib/rails/plugin/test.rb
index bd43cba688..40070c0eb3 100644
--- a/railties/lib/rails/plugin/test.rb
+++ b/railties/lib/rails/plugin/test.rb
@@ -1,7 +1,7 @@
-require_relative "../test_unit/minitest_plugin"
+require_relative "../test_unit/runner"
+require_relative "../test_unit/reporter"
 
 Rails::TestUnitReporter.executable = "bin/test"
 
-Minitest.run_via = :rails
-
-require "active_support/testing/autorun"
+Rails::TestUnit::Runner.parse_options(ARGV)
+Rails::TestUnit::Runner.run(ARGV)
diff --git a/railties/lib/rails/test_help.rb b/railties/lib/rails/test_help.rb
index 05048eb2e1..33b6740cf1 100644
--- a/railties/lib/rails/test_help.rb
+++ b/railties/lib/rails/test_help.rb
@@ -2,7 +2,6 @@
 # so fixtures aren't loaded into that environment
 abort("Abort testing: Your Rails environment is running in production mode!") if Rails.env.production?
 
-require_relative "test_unit/minitest_plugin"
 require "active_support/test_case"
 require "action_controller"
 require "action_controller/test_case"
diff --git a/railties/lib/rails/test_unit/line_filtering.rb b/railties/lib/rails/test_unit/line_filtering.rb
index 32ba744701..289afae331 100644
--- a/railties/lib/rails/test_unit/line_filtering.rb
+++ b/railties/lib/rails/test_unit/line_filtering.rb
@@ -1,78 +1,12 @@
 require "method_source"
+require "rails/test_unit/runner"
 
 module Rails
   module LineFiltering # :nodoc:
     def run(reporter, options = {})
-      if options[:patterns] && options[:patterns].any? { |p| p =~ /:\d+/ }
-        options[:filter] = \
-          CompositeFilter.new(self, options[:filter], options[:patterns])
-      end
+      options[:filter] = Rails::TestUnit::Runner.compose_filter(self, options[:filter])
 
       super
     end
   end
-
-  class CompositeFilter # :nodoc:
-    attr_reader :named_filter
-
-    def initialize(runnable, filter, patterns)
-      @runnable = runnable
-      @named_filter = derive_named_filter(filter)
-      @filters = [ @named_filter, *derive_line_filters(patterns) ].compact
-    end
-
-    # Minitest uses === to find matching filters.
-    def ===(method)
-      @filters.any? { |filter| filter === method }
-    end
-
-    private
-      def derive_named_filter(filter)
-        if filter.respond_to?(:named_filter)
-          filter.named_filter
-        elsif filter =~ %r%/(.*)/% # Regexp filtering copied from Minitest.
-          Regexp.new $1
-        elsif filter.is_a?(String)
-          filter
-        end
-      end
-
-      def derive_line_filters(patterns)
-        patterns.flat_map do |file_and_line|
-          file, *lines = file_and_line.split(":")
-
-          if lines.empty?
-            Filter.new(@runnable, file, nil) if file
-          else
-            lines.map { |line| Filter.new(@runnable, file, line) }
-          end
-        end
-      end
-  end
-
-  class Filter # :nodoc:
-    def initialize(runnable, file, line)
-      @runnable, @file = runnable, File.expand_path(file)
-      @line = line.to_i if line
-    end
-
-    def ===(method)
-      return unless @runnable.method_defined?(method)
-
-      if @line
-        test_file, test_range = definition_for(@runnable.instance_method(method))
-        test_file == @file && test_range.include?(@line)
-      else
-        @runnable.instance_method(method).source_location.first == @file
-      end
-    end
-
-    private
-      def definition_for(method)
-        file, start_line = method.source_location
-        end_line = method.source.count("\n") + start_line - 1
-
-        return file, start_line..end_line
-      end
-  end
 end
diff --git a/railties/lib/rails/test_unit/minitest_plugin.rb b/railties/lib/rails/test_unit/minitest_plugin.rb
deleted file mode 100644
index 3571274bcd..0000000000
--- a/railties/lib/rails/test_unit/minitest_plugin.rb
+++ /dev/null
@@ -1,145 +0,0 @@
-require "active_support/core_ext/module/attribute_accessors"
-require_relative "reporter"
-require_relative "test_requirer"
-require "shellwords"
-
-module Minitest
-  class SuppressedSummaryReporter < SummaryReporter
-    # Disable extra failure output after a run if output is inline.
-    def aggregated_results(*)
-      super unless options[:output_inline]
-    end
-  end
-
-  def self.plugin_rails_options(opts, options)
-    executable = ::Rails::TestUnitReporter.executable
-    opts.separator ""
-    opts.separator "Usage: #{executable} [options] [files or directories]"
-    opts.separator "You can run a single test by appending a line number to a filename:"
-    opts.separator ""
-    opts.separator "    #{executable} test/models/user_test.rb:27"
-    opts.separator ""
-    opts.separator "You can run multiple files and directories at the same time:"
-    opts.separator ""
-    opts.separator "    #{executable} test/controllers test/integration/login_test.rb"
-    opts.separator ""
-    opts.separator "By default test failures and errors are reported inline during a run."
-    opts.separator ""
-
-    opts.separator "Rails options:"
-    opts.on("-e", "--environment ENV",
-            "Run tests in the ENV environment") do |env|
-      options[:environment] = env.strip
-    end
-
-    opts.on("-b", "--backtrace",
-            "Show the complete backtrace") do
-      options[:full_backtrace] = true
-    end
-
-    opts.on("-d", "--defer-output",
-            "Output test failures and errors after the test run") do
-      options[:output_inline] = false
-    end
-
-    opts.on("-f", "--fail-fast",
-            "Abort test run on first failure or error") do
-      options[:fail_fast] = true
-    end
-
-    opts.on("-c", "--[no-]color",
-            "Enable color in the output") do |value|
-      options[:color] = value
-    end
-
-    opts.on("-w", "--warnings",
-            "Enable ruby warnings") do
-      $VERBOSE = true
-    end
-
-    options[:color] = true
-    options[:output_inline] = true
-    options[:patterns] = opts.order! unless run_via.rake?
-  end
-
-  def self.rake_run(patterns, exclude_patterns = []) # :nodoc:
-    self.run_via = :rake unless run_via.set?
-    ::Rails::TestRequirer.require_files(patterns, exclude_patterns)
-    autorun
-  end
-
-  module RunRespectingRakeTestopts
-    def run(args = [])
-      if run_via.rake?
-        args = Shellwords.split(ENV["TESTOPTS"] || "")
-      end
-
-      super
-    end
-  end
-
-  singleton_class.prepend RunRespectingRakeTestopts
-
-  # Owes great inspiration to test runner trailblazers like RSpec,
-  # minitest-reporters, maxitest and others.
-  def self.plugin_rails_init(options)
-    ENV["RAILS_ENV"] = options[:environment] || "test"
-
-    # If run via `ruby` we've been passed the files to run directly, or if run
-    # via `rake` then they have already been eagerly required.
-    unless run_via.ruby? || run_via.rake?
-      # If there are no given patterns, we can assume that the user
-      # simply runs the `bin/rails test` command without extra arguments.
-      if options[:patterns].empty?
-        ::Rails::TestRequirer.require_files(options[:patterns], ["test/system/**/*"])
-      else
-        ::Rails::TestRequirer.require_files(options[:patterns])
-      end
-    end
-
-    unless options[:full_backtrace] || ENV["BACKTRACE"]
-      # Plugin can run without Rails loaded, check before filtering.
-      Minitest.backtrace_filter = ::Rails.backtrace_cleaner if ::Rails.respond_to?(:backtrace_cleaner)
-    end
-
-    # Replace progress reporter for colors.
-    reporter.reporters.delete_if { |reporter| reporter.kind_of?(SummaryReporter) || reporter.kind_of?(ProgressReporter) }
-    reporter << SuppressedSummaryReporter.new(options[:io], options)
-    reporter << ::Rails::TestUnitReporter.new(options[:io], options)
-  end
-
-  def self.run_via=(runner)
-    if run_via.set?
-      raise ArgumentError, "run_via already assigned"
-    else
-      run_via.runner = runner
-    end
-  end
-
-  class RunVia
-    attr_accessor :runner
-    alias set? runner
-
-    # Backwardscompatibility with Rails 5.0 generated plugin test scripts.
-    def []=(runner, *)
-      @runner = runner
-    end
-
-    def ruby?
-      runner == :ruby
-    end
-
-    def rake?
-      runner == :rake
-    end
-  end
-
-  mattr_reader :run_via, default: RunVia.new
-end
-
-# Put Rails as the first plugin minitest initializes so other plugins
-# can override or replace our default reporter setup.
-# Since minitest only loads plugins if its extensions are empty we have
-# to call `load_plugins` first.
-Minitest.load_plugins
-Minitest.extensions.unshift "rails"
diff --git a/railties/lib/rails/test_unit/runner.rb b/railties/lib/rails/test_unit/runner.rb
new file mode 100644
index 0000000000..8018ef9d02
--- /dev/null
+++ b/railties/lib/rails/test_unit/runner.rb
@@ -0,0 +1,140 @@
+require "shellwords"
+require "method_source"
+require "rake/file_list"
+require "active_support/core_ext/module/attribute_accessors"
+
+module Rails
+  module TestUnit
+    class Runner
+      mattr_reader :filters, default: []
+
+      class << self
+        def options(opts)
+          opts.on("--warnings", "-w", "Run with Ruby warnings enabled") {}
+          opts.on("--environment", "-e", "Run tests in the ENV environment") {}
+        end
+
+        def parse_options(argv)
+          # Perform manual parsing and cleanup since option parser raises on unknown options.
+          env_index = argv.index("--environment") || argv.index("-e")
+          if env_index
+            argv.delete_at(env_index)
+            environment = argv.delete_at(env_index).strip
+          end
+          ENV["RAILS_ENV"] = environment || "test"
+
+          w_index = argv.index("--warnings") || argv.index("-w")
+          $VERBOSE = argv.delete_at(w_index) if w_index
+        end
+
+        def rake_run(argv = [])
+          ARGV.replace Shellwords.split(ENV["TESTOPTS"] || "")
+
+          run(argv)
+        end
+
+        def run(argv = [])
+          load_tests(argv)
+
+          require "active_support/testing/autorun"
+        end
+
+        def load_tests(argv)
+          patterns = extract_filters(argv)
+
+          tests = Rake::FileList[patterns.any? ? patterns : "test/**/*_test.rb"]
+          tests.exclude("test/system/**/*") if patterns.empty?
+
+          tests.to_a.each { |path| require File.expand_path(path) }
+        end
+
+        def compose_filter(runnable, filter)
+          if filters.any? { |_, lines| lines.any? }
+            CompositeFilter.new(runnable, filter, filters)
+          else
+            filter
+          end
+        end
+
+        private
+          def extract_filters(argv)
+            argv.select { |arg| arg =~ /^\w+\// }.map do |path|
+              case
+              when path =~ /(:\d+)+$/
+                file, *lines = path.split(":")
+                filters << [ file, lines ]
+                file
+              when Dir.exist?(path)
+                "#{path}/**/*_test.rb"
+              else
+                filters << [ path, [] ]
+                path
+              end
+            end
+          end
+      end
+    end
+
+    class CompositeFilter # :nodoc:
+      attr_reader :named_filter
+
+      def initialize(runnable, filter, patterns)
+        @runnable = runnable
+        @named_filter = derive_named_filter(filter)
+        @filters = [ @named_filter, *derive_line_filters(patterns) ].compact
+      end
+
+      # Minitest uses === to find matching filters.
+      def ===(method)
+        @filters.any? { |filter| filter === method }
+      end
+
+      private
+        def derive_named_filter(filter)
+          if filter.respond_to?(:named_filter)
+            filter.named_filter
+          elsif filter =~ %r%/(.*)/% # Regexp filtering copied from Minitest.
+            Regexp.new $1
+          elsif filter.is_a?(String)
+            filter
+          end
+        end
+
+        def derive_line_filters(patterns)
+          patterns.flat_map do |file, lines|
+            if lines.empty?
+              Filter.new(@runnable, file, nil) if file
+            else
+              lines.map { |line| Filter.new(@runnable, file, line) }
+            end
+          end
+        end
+    end
+
+    class Filter # :nodoc:
+      def initialize(runnable, file, line)
+        @runnable, @file = runnable, File.expand_path(file)
+        @line = line.to_i if line
+      end
+
+      def ===(method)
+        return unless @runnable.method_defined?(method)
+
+        if @line
+          test_file, test_range = definition_for(@runnable.instance_method(method))
+          test_file == @file && test_range.include?(@line)
+        else
+          @runnable.instance_method(method).source_location.first == @file
+        end
+      end
+
+      private
+        def definition_for(method)
+          file, start_line = method.source_location
+          end_line = method.source.count("\n") + start_line - 1
+
+          return file, start_line..end_line
+        end
+    end
+  end
+end
diff --git a/railties/lib/rails/test_unit/test_requirer.rb b/railties/lib/rails/test_unit/test_requirer.rb
deleted file mode 100644
index 92e5fcf0bc..0000000000
--- a/railties/lib/rails/test_unit/test_requirer.rb
+++ /dev/null
@@ -1,31 +0,0 @@
-require "active_support/core_ext/object/blank"
-require "rake/file_list"
-
-module Rails
-  class TestRequirer # :nodoc:
-    class << self
-      def require_files(patterns, exclude_patterns = [])
-        patterns = expand_patterns(patterns)
-
-        file_list = Rake::FileList[patterns.compact.presence || "test/**/*_test.rb"]
-        file_list.exclude(exclude_patterns)
-
-        file_list.to_a.each do |file|
-          require File.expand_path(file)
-        end
-      end
-
-      private
-        def expand_patterns(patterns)
-          patterns.map do |arg|
-            arg = arg.gsub(/(:\d+)+?$/, "")
-            if Dir.exist?(arg)
-              "#{arg}/**/*_test.rb"
-            else
-              arg
-            end
-          end
-        end
-    end
-  end
-end
diff --git a/railties/lib/rails/test_unit/testing.rake b/railties/lib/rails/test_unit/testing.rake
index 486446b463..97dd5cef10 100644
--- a/railties/lib/rails/test_unit/testing.rake
+++ b/railties/lib/rails/test_unit/testing.rake
@@ -1,6 +1,6 @@
 gem "minitest"
 require "minitest"
-require_relative "minitest_plugin"
+require_relative "runner"
 
 task default: :test
 
@@ -9,9 +9,9 @@ task :test do
   $: << "test"
 
   if ENV.key?("TEST")
-    Minitest.rake_run([ENV["TEST"]])
+    Rails::TestUnit::Runner.rake_run([ENV["TEST"]])
   else
-    Minitest.rake_run(["test"], ["test/system/**/*"])
+    Rails::TestUnit::Runner.rake_run
   end
 end
 
@@ -29,28 +29,28 @@ namespace :test do
   ["models", "helpers", "controllers", "mailers", "integration", "jobs"].each do |name|
     task name => "test:prepare" do
       $: << "test"
-      Minitest.rake_run(["test/#{name}"])
+      Rails::TestUnit::Runner.rake_run(["test/#{name}"])
     end
   end
 
   task generators: "test:prepare" do
     $: << "test"
-    Minitest.rake_run(["test/lib/generators"])
+    Rails::TestUnit::Runner.rake_run(["test/lib/generators"])
   end
 
   task units: "test:prepare" do
     $: << "test"
-    Minitest.rake_run(["test/models", "test/helpers", "test/unit"])
+    Rails::TestUnit::Runner.rake_run(["test/models", "test/helpers", "test/unit"])
   end
 
   task functionals: "test:prepare" do
     $: << "test"
-    Minitest.rake_run(["test/controllers", "test/mailers", "test/functional"])
+    Rails::TestUnit::Runner.rake_run(["test/controllers", "test/mailers", "test/functional"])
   end
 
   desc "Run system tests only"
   task system: "test:prepare" do
     $: << "test"
-    Minitest.rake_run(["test/system"])
+    Rails::TestUnit::Runner.rake_run(["test/system"])
   end
 end
diff --git a/railties/test/application/test_runner_test.rb b/railties/test/application/test_runner_test.rb
index 8e0712fca2..c0027ab9a2 100644
--- a/railties/test/application/test_runner_test.rb
+++ b/railties/test/application/test_runner_test.rb
@@ -16,13 +16,13 @@ module ApplicationTests
     end
 
     def test_run_via_backwardscompatibility
-      require "rails/test_unit/minitest_plugin"
+      require "minitest/rails_plugin"
 
       assert_nothing_raised do
         Minitest.run_via[:ruby] = true
       end
 
-      assert_predicate Minitest.run_via, :ruby?
+      assert Minitest.run_via[:ruby]
     end
 
     def test_run_single_file
diff --git a/railties/test/test_unit/reporter_test.rb b/railties/test/test_unit/reporter_test.rb
index 98201394cd..42f973357b 100644
--- a/railties/test/test_unit/reporter_test.rb
+++ b/railties/test/test_unit/reporter_test.rb
@@ -70,7 +70,7 @@ class TestUnitReporterTest < ActiveSupport::TestCase
     @reporter.record(errored_test)
     @reporter.report
 
-    expect = %r{\AE\n\nError:\nTestUnitReporterTest::ExampleTest#woot:\nArgumentError: wups\n    No backtrace\n\nbin/rails test .*test/test_unit/reporter_test\.rb:\d+\n\n\z}
+    expect = %r{\AE\n\nError:\nTestUnitReporterTest::ExampleTest#woot:\nArgumentError: wups\n    \n\nbin/rails test .*test/test_unit/reporter_test\.rb:\d+\n\n\z}
     assert_match expect, @output.string
   end
 
@@ -150,7 +150,7 @@ class TestUnitReporterTest < ActiveSupport::TestCase
       colored = Rails::TestUnitReporter.new @output, color: true, output_inline: true
       colored.record(errored_test)
 
-      expected = %r{\e\[31mE\e\[0m\n\n\e\[31mError:\nTestUnitReporterTest::ExampleTest#woot:\nArgumentError: wups\n    No backtrace\n\e\[0m}
+      expected = %r{\e\[31mE\e\[0m\n\n\e\[31mError:\nTestUnitReporterTest::ExampleTest#woot:\nArgumentError: wups\n    \n\e\[0m}
       assert_match expected, @output.string
     end
   end
@@ -171,8 +171,11 @@ class TestUnitReporterTest < ActiveSupport::TestCase
     end
 
     def errored_test
+      error = ArgumentError.new("wups")
+      error.set_backtrace([ "some_test.rb:4" ])
+
       et = ExampleTest.new(:woot)
-      et.failures << Minitest::UnexpectedError.new(ArgumentError.new("wups"))
+      et.failures << Minitest::UnexpectedError.new(error)
       et
     end
 
diff --git a/tools/test.rb b/tools/test.rb
index 52e9c19198..774e4ec6c7 100644
--- a/tools/test.rb
+++ b/tools/test.rb
@@ -3,8 +3,10 @@ $: << File.expand_path("test", COMPONENT_ROOT)
 require "bundler"
 Bundler.setup
 
-require "rails/test_unit/minitest_plugin"
+require "rails/test_unit/runner"
+require "rails/test_unit/reporter"
 require "rails/test_unit/line_filtering"
+require "active_support"
 require "active_support/test_case"
 
 class << Rails
@@ -17,5 +19,6 @@ end
 
 ActiveSupport::TestCase.extend Rails::LineFiltering
 Rails::TestUnitReporter.executable = "bin/test"
-Minitest.run_via = :rails
-require "active_support/testing/autorun"
+
+Rails::TestUnit::Runner.parse_options(ARGV)
+Rails::TestUnit::Runner.run(ARGV)