Default to sorting user's test cases for now

Goals:

1. Default to :random for newly generated applications
2. Default to :sorted for existing applications with a warning
3. Only show the warning once
4. Only show the warning if the app actually uses AS::TestCase

Fixes #16769

2 files changed, 48 insertions, 1 deletions

diff --git a/activesupport/test/abstract_unit.rb b/activesupport/test/abstract_unit.rb
index 52fbaf8a85..f65ec962f9 100644
--- a/activesupport/test/abstract_unit.rb
+++ b/activesupport/test/abstract_unit.rb
@@ -42,4 +42,4 @@ require 'mocha/setup' # FIXME: stop using mocha
 # FIXME: we have tests that depend on run order, we should fix that and
 # remove this method call.
 require 'active_support/test_case'
-ActiveSupport::TestCase.my_tests_are_order_dependent!
+ActiveSupport::TestCase.test_order = :sorted
diff --git a/activesupport/test/test_case_test.rb b/activesupport/test/test_case_test.rb
index c93192f207..5e852c8050 100644
--- a/activesupport/test/test_case_test.rb
+++ b/activesupport/test/test_case_test.rb
@@ -172,3 +172,50 @@ class TestCaseTaggedLoggingTest < ActiveSupport::TestCase
     assert_match "#{self.class}: #{name}\n", @out.string
   end
 end
+
+class TestOrderTest < ActiveSupport::TestCase
+  def setup
+    @original_test_order = ActiveSupport::TestCase.test_order
+  end
+
+  def teardown
+    ActiveSupport::TestCase.test_order = @original_test_order
+  end
+
+  def test_defaults_to_sorted_with_warning
+    ActiveSupport::TestCase.test_order = nil
+
+    assert_equal :sorted, assert_deprecated { ActiveSupport::TestCase.test_order }
+
+    # It should only produce a deprecation warning the first time this is accessed
+    assert_equal :sorted, assert_not_deprecated { ActiveSupport::TestCase.test_order }
+    assert_equal :sorted, assert_not_deprecated { ActiveSupport.test_order }
+  end
+
+  def test_test_order_is_global
+    ActiveSupport::TestCase.test_order = :random
+
+    assert_equal :random, ActiveSupport.test_order
+    assert_equal :random, ActiveSupport::TestCase.test_order
+    assert_equal :random, self.class.test_order
+    assert_equal :random, Class.new(ActiveSupport::TestCase).test_order
+
+    ActiveSupport.test_order = :sorted
+
+    assert_equal :sorted, ActiveSupport.test_order
+    assert_equal :sorted, ActiveSupport::TestCase.test_order
+    assert_equal :sorted, self.class.test_order
+    assert_equal :sorted, Class.new(ActiveSupport::TestCase).test_order
+  end
+
+  def test_i_suck_and_my_tests_are_order_dependent!
+    ActiveSupport::TestCase.test_order = :random
+
+    klass = Class.new(ActiveSupport::TestCase) do
+      i_suck_and_my_tests_are_order_dependent!
+    end
+
+    assert_equal :alpha, klass.test_order
+    assert_equal :random, ActiveSupport::TestCase.test_order
+  end
+end