https://buildkite.com/rails/rails/builds/61362#99165d42-172d-4ad5-bf72-b29d8cd44f3e/995-1006

Fix #35665

```ruby
$ ARCONN=mysql2 bin/test test/cases/scoping/named_scoping_test.rb test/cases/tasks/database_tasks_test.rb test/cases/associations/cascaded_eager_loading_test.rb test/cases/associations/eager_singularization_test.rb -n "/^(?:NamedScopingTest#(?:test_many_should_not_fire_query_if_scope_loaded)|ActiveRecord::DatabaseTasksDumpSchemaCacheTest#(?:test_dump_schema_cache)|CascadedEagerLoadingTest#(?:test_eager_association_loading_with_has_many_sti_and_subclasses)|EagerSingularizationTest#(?:test_eager_no_extra_singularization_has_many_through_belongs_to))$/" --seed 16818
Using mysql2
Run options: -n "/^(?:NamedScopingTest#(?:test_many_should_not_fire_query_if_scope_loaded)|ActiveRecord::DatabaseTasksDumpSchemaCacheTest#(?:test_dump_schema_cache)|CascadedEagerLoadingTest#(?:test_eager_association_loading_with_has_many_sti_and_subclasses)|EagerSingularizationTest#(?:test_eager_no_extra_singularization_has_many_through_belongs_to))$/" --seed 16818

...F

Failure:
CascadedEagerLoadingTest#test_eager_association_loading_with_has_many_sti_and_subclasses [/home/yahonda/git/rails/activerecord/test/cases/associations/cascaded_eager_loading_test.rb:124]:
1 instead of 0 queries were executed.
Queries:
SHOW FULL FIELDS FROM `topics`.
Expected: 0
  Actual: 1

bin/test test/cases/associations/cascaded_eager_loading_test.rb:119

Finished in 6.894609s, 0.5802 runs/s, 1.0153 assertions/s.
4 runs, 7 assertions, 1 failures, 0 errors, 0 skips
$
```

https://travis-ci.org/rails/rails/jobs/491045821#L1528-L1531

cherry-picked from https://github.com/rails/rails/pull/33763

`topic` and `reply` belongs_to associations on `SillyReply` are defined
with the same `foreign_key` (`parent_id`) and `counter_cache`
(`replies_count`) columns.
This would cause unintentional side-effect (e.g. saving `SillyReply`
object would cause double increment `replies_count`), so it is better to
avoid that side-effect.

Follow up of #31390.

This reverts commit 3420a145, reversing
changes made to afb66a5a.

These `assert_nothing_raised` are covered by following assertions.

This change reverted in eac6f369 but it is needed for data integrity.
See #25328.

Revert "Merge pull request #27636 from mtsmfm/disable-referential-integrity-without-superuser-privilege-take-2"

This reverts commit c1faca63, reversing
changes made to 8c658a0e.

See https://github.com/rails/rails/pull/27636#issuecomment-297534129

Re-create https://github.com/rails/rails/pull/21233

eeac6151 was reverted (127509c0) because it breaks tests.

----------------

ref: 72c15572

- We must use `authors` fixture with `author_addresses` because of its foreign key constraint.
- Tests require PostgreSQL >= 9.4.2 because it had a bug about `ALTER CONSTRAINTS` and fixed in 9.4.2.

Revert "Merge pull request #21233 from mtsmfm/disable-referential-integrity-without-superuser-privileges"

This reverts commit eeac6151, reversing
changes made to 5c40239d.

Reason: Broke the isolated tests.
https://travis-ci.org/rails/rails/builds/188721346

ref: 72c15572

- We must use `authors` fixture with `author_addresses` because of its foreign key constraint.
- Tests require PostgreSQL >= 9.4.2 because it had a bug about `ALTER CONSTRAINTS` and fixed in 9.4.2.

assert [1, 3].includes?(2) fails with unhelpful "Asserting failed" message

assert_includes [1, 3], 2 fails with "Expected [1, 3] to include 2" which makes it easier to debug and more obvious what went wrong

Style/SpaceBeforeBlockBraces
Style/SpaceInsideBlockBraces
Style/SpaceInsideHashLiteralBraces

Fix all violations in the repository.

The current code base is not uniform. After some discussion,
we have chosen to go with double quotes by default.

Reliant on https://github.com/rails/rails/pull/15747 but pulled to a
separate PR to reduce noise. `has_many :through` associations have the
undocumented behavior of automatically detecting counter caches.
However, the way in which it does so is inconsistent with counter caches
everywhere else, and doesn't actually work consistently.

As with normal `has_many` associations, the user should specify the
counter cache on the `belongs_to`, if they'd like it updated.

https://github.com/rails/rails/commit/2075f39d726cef361170218fd16421fc52bed5a8 introduced a regression in includes/preloades
by calling `read_attribute` on an association when preloading takes places, instead of using loaded records in `association.target`.

tl;dr

Records are not made properly available via `read_attribute` when preloding in simultaneous,
but value of `@loaded` is already set true, and records concatenated in `association.target` on an association object.
When `@loaded` is true we return an object of `AlreadyLoaded` in preload_for. In `AlreadyLoaded` to return preloaded
records we make wrong use of `read_attribute`, instead of `target` records.

The regression is fixed by making use of the loaded records in `association.target` when the preloading takes place.

Fixes #13437

We moved more and more away from passing options to finder / calculation
methods. The `:distinct` option in `#count` was one of the remaining places.
Since we can now combine `Relation#distinct` with `Relation#count` the option
is no longer necessary and can be deprecated.

It doesn't serve much purpose now that ActiveRecord::Base.all returns a
Relation.

The code is moved to active_record_deprecated_finders.

Previously it returned an Array.

If you want an array, call e.g. `Post.to_a` rather than `Post.all`. This
is more explicit.

In most cases this should not break existing code, since
Relations use method_missing to delegate unknown methods to #to_a
anyway.

See the CHANGELOG for details.

Fixes #950.

This reverts commit c99d507f.

Refactor Active Record test connection setup. Please see the RUNNING_UNIT_TESTS file for details, but essentially you can now configure things in test/config.yml. You can also run tests directly via the command line, e.g. ruby path/to/test.rb (no rake needed, uses default db connection from test/config.yml). This will help us fix the CI by enabling us to isolate the different Rails versions to different databases.