Add docs for AS::TestCase::test_order

Document `test_order` and `test_order=` from `ActiveSupport::TestCase`.

[ci skip]

2 files changed, 17 insertions, 2 deletions

diff --git a/activesupport/lib/active_support.rb b/activesupport/lib/active_support.rb
index 94468240a4..34040e9d33 100644
--- a/activesupport/lib/active_support.rb
+++ b/activesupport/lib/active_support.rb
@@ -73,11 +73,11 @@ module ActiveSupport
 
   @@test_order = nil
 
-  def self.test_order=(new_order)
+  def self.test_order=(new_order) # :nodoc:
     @@test_order = new_order
   end
 
-  def self.test_order
+  def self.test_order # :nodoc:
     @@test_order
   end
 end
diff --git a/activesupport/lib/active_support/test_case.rb b/activesupport/lib/active_support/test_case.rb
index a4ba5989b1..98b68455ab 100644
--- a/activesupport/lib/active_support/test_case.rb
+++ b/activesupport/lib/active_support/test_case.rb
@@ -16,10 +16,25 @@ module ActiveSupport
     Assertion = Minitest::Assertion
 
     class << self
+      # Sets the order in which test cases are run.
+      #
+      #   ActiveSupport::TestCase.test_order = :random # => :random
+      #
+      # Valid values are:
+      # * +:random+   (to run tests in random order)
+      # * +:parallel+ (to run tests in parallel)
+      # * +:sorted+   (to run tests alphabetically by method name)
+      # * +:alpha+    (equivalent to +:sorted+)
       def test_order=(new_order)
         ActiveSupport.test_order = new_order
       end
 
+      # Returns the order in which test cases are run.
+      #
+      #   ActiveSupport::TestCase.test_order # => :sorted
+      #
+      # Possible values are +:random+, +:parallel+, +:alpha+, +:sorted+.
+      # Defaults to +:sorted+.
       def test_order
         test_order = ActiveSupport.test_order