As part of refactoring mutation detection to be more performant, we
introduced the concept of `original_value` to `Attribute`. This was not
overridden in `Attribute::Uninitialized` however, so assigning ot an
uninitialized value and calling `.changed?` would raise
`NotImplementedError`.

We are using a sentinel value rather than checking the result of
`original_attribute.initialized?` in `changed?` because `original_value`
might go through more than one node in the tree.

Fixes #25228

add missing "as" to Engines doc page [ci skip]

it reads a bit awkwardly without it.

Currently CI is broken due to 56a61e0c and c4cb6862. This occurred because
the failures are not present on SQLite which is what I normally run
locally before pushing.

The optimizations to our YAML size were dropping mutations, as
`with_type` didn't set the previous value if it'd already been read
(that method was never really designed to be used with values on
individual objects, it was previously only used for defaults). I'm
questioning whether there's a better place to be handling the exclusion
of the type, but this will fix the failing build.

Additionally, there was a bug in `remove_foreign_key` if you passed it
an options hash containing `to_table`. This now occurs whenever removing
a reference, as we always normalize to a hash.

[Sean Griffin & Ryuta Kamizono]

fix typo [ci skip]

Collapse all new default initializers into a single file

- Adjusted tests also for this new behavior.
- Based on the discussion in
  https://github.com/rails/rails/pull/25184#issuecomment-222454583.

This reduces the size of a YAML encoded Active Record object by ~80%
depending on the number of columns. There were a number of wasteful
things that occurred when we encoded the objects before that have
resulted in numerous wins

- We were emitting the result of `attributes_before_type_cast` as a hack
  to work around some laziness issues
- The name of an attribute was emitted multiple times, since the
  attribute objects were in a hash keyed by the name. We now store them
  in an array instead, and reconstruct the hash using the name
- The types were included for every attribute. This would use backrefs
  if multiple objects were encoded, but really we don't need to include
  it at all unless it differs from the type at the class level. (The
  only time that will occur is if the field is the result of a custom
  select clause)
- `original_attribute:` was included over and over and over again since
  the ivar is almost always `nil`. We've added a custom implementation
  of `encode_with` on the attribute objects to ensure we don't write the
  key when the field is `nil`.

This isn't without a cost though. Since we're no longer including the
types, an object can find itself in an invalid state if the type changes
on the class after serialization. This is the same as 4.1 and earlier,
but I think it's worth noting.

I was worried that I'd introduce some new state bugs as a result of
doing this, so I've added an additional test that asserts mutation not
being lost as the result of YAML round tripping.

Fixes #25145

- The `Project` model should have been removed in 46893929.
- The superfluous require was added in 605c6455.

Closes #25215
Signed-off-by: NJeremy Daer <jeremydaer@gmail.com>

[Action Cable] Add `WebSocket` and `logger` configuration options

[Javan Makhmali, Jon Moss]

The code incorrectly assumes that the option was written as
`foreign_key: true`, but that is not always the case. This now mirrors
the behavior of reverting `add_foreign_key`. The code was changed to use
kwargs while I was touching it, as well.

This could really use a refactoring to go through the same code paths as
`add_refernce` in the future, so we don't duplicate default values.

Fixes #25169

Action Cable: Tune Sauce Labs tests

Do not include default column limit in schema.rb

Prior to this change, we would get collisions if Active Record objects
of different classes with the same ID were used as keys of the same
hash. It bothers me slightly that we have to allocate inside of this
method, but Ruby doesn't provide any way to hash multiple values without
allocation

- Remove dead classes / dead code
- Move class definitions to where they are used, don't define in a
  shared space

Cuts down the number of concurrent Sauce Labs VMs we need to spin up. Can add specific versions back in to target regressions if need be.

Fix Typo and Grammar [ci skip]

Follow up of #20815.

```ruby
class CreatePeople < ActiveRecord::Migration[5.0]
  def change
    create_table :people do |t|
      t.integer :int
      t.bigint :bint
      t.text :txt
      t.binary :bin
    end
  end
end
```

Result.

In postgresql and sqlite3 adapters:

```ruby
ActiveRecord::Schema.define(version: 20160531141018) do

  create_table "people", force: :cascade do |t|
    t.integer "int"
    t.bigint  "bint"
    t.text    "txt"
    t.binary  "bin"
  end

end
```

In mysql2 adapter:

```ruby
ActiveRecord::Schema.define(version: 20160531141018) do

  create_table "people", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4" do |t|
    t.integer "int"
    t.bigint  "bint"
    t.text    "txt",  limit: 65535
    t.binary  "bin",  limit: 65535
  end

end
```

After this patch:

```ruby
ActiveRecord::Schema.define(version: 20160531141018) do

  create_table "people", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4" do |t|
    t.integer "int"
    t.bigint  "bint"
    t.text    "txt"
    t.binary  "bin"
  end

end
```

This behavior was broken by 36e9be85. When the value is assigned
directly, either through mass assignment or directly assigning a hash,
the hash gets passed through to this writer method directly. While this
is intended to handle certain cases, when an explicit converter has been
provided, we should continue to use that instead. The positioning of the
added guard caused the new behavior to override that case.

Fixes #25210

Move `Workshop` class definition

We should define it only where we need it, not in the global abstract
unit 😬

Reuse a result of `table.associated_table(column)` in `AssociationQueryHandler.value_for`

Currently `exists?` does some hackery where it assumes that we can join
onto anything that we passed to `eager_load` or `includes`, which
doesn't work if we are joining onto a polymorphic association.

Actually figuring out if we want to include something would require
knowledge deep within the join dependency module, which is hard to pull
up. The simplest solution is just to pass a flag down that says we're
not actually going to try to eager load any of the data. It's not the
solution I'd like, but that code really needs to be untangled before we
can do much with it.

This is another attempt at 6d5b1fdf which should address the concerns
that led to reverting it in 4ecabed2.

use OpenSSL::Cipher instead of deprecated OpenSSL::Cipher::Cipher

We now use default procs inside of the errors object, which gets
included by default when marshaling anything that includes
`ActiveModel::Validations`. This means that Active Record objects cannot
be marshalled. We strip and apply the default proc ourselves. This will
ensure the objects are YAML serializable as well, since YAML falls back
to marshal implementations now. This is less important, however, as the
errors aren't included when dumping Active Record objects.

This commit does not include a changelog entry, as 5.0 is still in RC
status at the time of writing, and 5.0.0 will not release with the bug
this fixes.

Fixes #25165

Fix migration class names in tests

Add a missing capital letter and avoid using absolute links to the
API because they may refer to out-dated documentation on the Edge
site.

Based on https://github.com/rails/rails/pull/25192#discussion_r65018222 and http://ruby-doc.org/stdlib-1.9.3/libdoc/openssl/rdoc/OpenSSL/Cipher/Cipher.html

Requesting documentation update

Change some establish_connection logic

Move new default initializers into separate directory

[ci skip]Fix wrong require path raising LoadError