add message to `assert` in `assert_enqueued_with`
ar/connection_pool: honor overriden rack.test in middleware

Honoring an overidden `rack.test` allows testing closed connection between
multiple requests. This is useful if you're working on database resiliency, to
ensure the connection is in the expected state from one request to another on
the same worker.
Added test for exception message for validate method

- Test case for https://github.com/rails/rails/pull/16851
Merge pull request #17022 from prathamesh-sonpatki/test-for-validate-message

Added test for exception message for validate method
Merge pull request #17005 from y-yagi/fix_aj_test_helper

add message to `assert` in `assert_enqueued_with`
Added note about updating pull requests by force push

- Added note about force pushing same branch to update a existing pull
  request instead of opening new one in contributing guide.
- [ci skip]
Fix loading fixtures in engine tests

fixture_path is a class attribute of ActiveSupport::TestCase, so
ActiveSupport::TestCase.method_defined?(:fixture_path=) would always
return false.

This should fix #4971
Merge pull request #17026 from prathamesh-sonpatki/mention-updating-pull-requests

Added note about updating pull requests by force push
Merge pull request #17029 from grk/fix-loading-fixtures-in-engine-tests

Fix loading fixtures in engine tests
[CI SKIP] Improve force push note.
Merge pull request #17032 from tgxworld/update_contributing_guide

[CI SKIP] Improve force push note.
Merge pull request #17020 from Sirupsen/ar-override-rack-test

activerecord/connection_pool: honor overidden rack.test in tests
AR::UnknownAttributeError should include the class name of a record

This would be helpful if 2 models have an attribute that has a similar
name to the other. e.g:

before:

    User.new(name: "Yuki Nishijima", projects_attributes: [{name: "kaminari"}])
    # => ActiveRecord::UnknownAttributeError: unknown attribute: name

after:

    User.new(name: "Yuki Nishijima", projects_attributes: [{name: "kaminari"}])
    # => ActiveRecord::UnknownAttributeError: unknown attribute on User: name