- If the attribute is not changed, then update_attribute does not run
  SQL query, this effectively means that no change was made to the
  attribute.
- This change was made in https://github.com/rails/rails/commit/0fcd4cf5
  to avoid a SQL call.
- But the change resulted into `nil` being returned when there was no
  change in the attribute value.
- This commit corrects the behavior to return true if there is no change
  in attribute value. This is same as previous behavior of Rails 4.2
  plus benefit of no additional SQL call.
- Fixes #26593.

When the association is autosaved we were storing the details with
string keys. This was creating inconsistency with other details that are
added using the `Errors#add` method. It was also inconsistent with the
`Errors#messages` storage.

To fix this inconsistency we are always storing with symbols. This will
cause a small breaking change because in those cases the details could
be accessed as strings keys but now it can not.

The reason that we chose to do this breaking change is because `#details`
should be considered a low level object like `#messages` is.

Fix #26499.

[Rafael Mendonça França + Marcus Vieira]

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

[fixes #26441]

Without this the changes to the lock version column will stick around
even after `touch` returns.

Before:

    model.touch
    model.changes
    # => {"lock_version"=>[0, "1"]}

After:

    model.touch
    model.changes
    # {}

All indentation was normalized by rubocop auto-correct at 80e66cc4.
But comments was still kept absolute position. This commit aligns
comments with method definitions for consistency.

* activerecord/mysql2: Avoid setting @connection to nil, just close it

Backport of https://github.com/rails/rails/pull/26434

* Add a CHANGELOG entry

Make name of attribute medium instead of normal

If using namespaced fixtures, get following Ruby warning.

```
activerecord/lib/active_record/fixtures.rb:922: warning: method redefined; discarding old admin_foos
activerecord/lib/active_record/fixtures.rb:922: warning: previous definition of admin_foos was here
```

This is happening because of the multiple set the same path when setting the
fixture name. Fix to remove the duplicate path.

The `elsif` branch is completely duplicated with `else` branch.

Passing `FakeColumn` was removed at #15336 therefore
`test_string_with_crazy_column` is duplicated with
`test_quote_string_no_column`.

`Mutex` was removed at 8eb7561a.

`column_for` was changed to `type_for` to return `type` object at
36bd52b4. But variable name is still `column`. It is very confusing.
Rename variable name `column` to `type` for readability.

This comment was added at eaf54865 but already implemented.

`CollectionAssociation` is internal class and `uniq` is not called.

In most case `where` is called with passed hash. In the case
initializing `binds` is unnecessary.

By doing `@connection = nil` that means that we need nil checks before it
is used anywhere, but we weren't doing those checks.  Instead, we get a
NoMethodError after using a connection after it fails to reconnect.

Neither of the other adapters set @connection to nil, just the mysql2
adapter. By just closing it, we avoid the need to check if we have a
connection object and it will produce an appropriate exception when used.

Recently, the Rails team made an effort to keep the source code consistent, using Ruboco
(bb1ecdcc and below). Some of the case
statements were missed.

This changes the case statements' formatting and is consistent with changes
in 810dff7c and db63406c.

Bang methods of `AR::QueryMethods` are used only internally.
We only use `left_outer_joins!`, so we can remove this alias.

Already checked `if !find_target? || loaded?`, unnecessary `!loaded?` in
elsif condition.

Simply use its own method because `CollectionProxy` inherits `Relation`.

Follow up to caa178c1.

caa178c1 updated all code which sets inverse instances on newly loaded
associations to use block. But `SingularAssociation` was forgotten it.

All indentation was normalized by rubocop auto-correct at 80e66cc4.
But heredocs was still kept absolute position. This commit aligns
heredocs indentation for consistency.

to address BasicsTest#test_readonly_attributes failure #26368

It reproduces only when both of these conditions are satisfied:

- Other test files `autosave_association_test.rb` or `where_test.rb`
  which executes `require "models/comment"` then `require "models/post"`
- When `autosave_association_test.rb` or `where_test.rb` executed before `base_test.rb`

The fact that this only includes column names is an oversight.

There are some minor changes to the point type as I had forgotten that
this will affect the behavior of `t.point` in migrations and the schema
dumper so we need to handle those as well.

I'll say this again so I can convince myself to come up with a better
structure... TYPES SHOULD NOT CARE ABOUT SCHEMA DUMPING AND WE NEED TO
BETTER SEPARATE THESE.

This reverts commit 3a1f6fe7.

This commit takes the code in a direction that I am looking to avoid.
The predicate builder should be purely concerned with AST construction
as it matters to methods like `where`. Things like case sensitivity
should continue to be handled elsewhere.

I still think that this is something that should be handled in the pg
gem, but it's not going to end up happening there so we'll do it here
instead. Once we bump to pg 0.19 we can pass the encoding to the
`encode` method instead.

This issue occurs because C has no concept of encoding (or strings,
really). The bytes that we pass here when sending the value to the
database will always be interpreted as whatever encoding the connection
is currently configured to use. That means that roundtripping to the
database will lose no information

However, after assigning we round trip through our type system without
hitting the database. The only way that we can do the "correct" thin
here would be to actually give a reference to the connection to the
array type and have it check the current value of the connection's
encoding -- which I'm strongly opposed to. We could also pass in the
encoding when it's constructed, but since that can change independently
of the type I'm not a huge fan of that either.

This feels like a reasonable middle ground, where if we have an array of
strings we simply use the encoding of the string we're given.

Fixes #26326.

This was almost every case where we are overriding `respond_to?` in a
way that mirrors a parallel implementation of `method_missing`. There is
one remaining case in Active Model that should probably do the same
thing, but had a sufficiently strange implementation that I want to
investigate it separately.

Fixes #26333.

If a parent association was accessed in an `after_find` or
`after_initialize` callback, it would always end up loading the
association, and then immediately overwriting the association we just
loaded. If this occurred in a way that the parent's `current_scope` was
set to eager load the child, this would result in an infinite loop and
eventually overflow the stack.

For records that are created with `.new`, we have a mechanism to
perform an action before the callbacks are run. I've introduced the same
code path for records created with `instantiate`, and updated all code
which sets inverse instances on newly loaded associations to use this
block instead.

Fixes #26320.

Rails dropped Ruby 1.9 support, but this comment still true.