`SetupAndTeardown` has few caveats that breaks libraries:

- In #32472 I introduced a fix in order for all `after_teardown` method provided by libraries and Rails to run, even if the application's `teardown` method raised an error (That's the default minitest behavior). However this change wasn't enough and doesn't take in consideration the ancestors chain.
  If a library's module containing an `after_teardown` method get included after the `SetupAndTeardown` module (one example is the [ActiveRecord::TestFixtures module](https://github.com/rails/rails/blob/7d2400ab61c8e3ed95e14d03ba3844e8ba2e36e4/activerecord/lib/active_record/fixtures.rb#L855-L856), then the ancestors of the test class would look something like
  ```ruby
    class MyTest < ActiveSupport::TestCase
    end

    puts MyTest.ancestors # [MyTest, ActiveSupport::TestCase, ActiveRecord::TestFixtures, ActiveSupport::Testing::SetupAndTeardown]
  ```
  Any class/module in the ancestors chain that are **before** the `ActiveSupport::Testing::SetupAndTeardown` will behave incorrectly:
    - Their `before_setup` method will get called **after** all regular setup method
    - Their `after_teardown` method won't even get called in case an exception is raised inside a regular's test `teardown`

  A simple reproduction script of the problem here https://gist.github.com/Edouard-chin/70705542a59a8593f619b02e1c0a188c

- One solution to this problem is to have the `AS::SetupAndTeardown` module be the very first in the ancestors chain. By doing that we ensure that no `before_setup` / `after_teardown` get executed prior to running the teardown callbacks

1 files changed, 1 insertions, 1 deletions

diff --git a/activesupport/lib/active_support/test_case.rb b/activesupport/lib/active_support/test_case.rb
index 4e42db4500..f17743b6db 100644
--- a/activesupport/lib/active_support/test_case.rb
+++ b/activesupport/lib/active_support/test_case.rb
@@ -130,7 +130,7 @@ module ActiveSupport
     alias_method :method_name, :name
 
     include ActiveSupport::Testing::TaggedLogging
-    include ActiveSupport::Testing::SetupAndTeardown
+    prepend ActiveSupport::Testing::SetupAndTeardown
     include ActiveSupport::Testing::Assertions
     include ActiveSupport::Testing::Deprecation
     include ActiveSupport::Testing::TimeHelpers