```
[NoMethodError]: undefined method `state' for nil:NilClass  Method:[rescue in block in refresh]
```

In `within_new_transaction`, there is the possibility that
`begin_transaction` returns a `nil`. (i.e.: so `transaction = nil`)
So this method is checking `transaction` for nil in 2 spots.

Unfortunately, there is one line that is not checking `transaction` for `nil`
That line, `commit_transaction`, throws an exception for us in AR 5.0.0.1

The problem with the method is finally realized in the error checking itself.
it calls `transaction.state` (i.e.: nil.state) and that is the final exception
raised.

The actual underlying (user) issue is hidden by this line.

Solution is test transaction for nil.

Resolve Minitest 6 deprecation in assert_no_changes

These changes resolve a deprecation warning in `assert_no_changes`
when asserting that an expression evaluates to `nil` before and after
the passed block is evaluated.

The smallest demonstration of this edge case:

```ruby
assert_no_changes "nil" do
  true # noop
end
```

Under the covers, this is evaluating

```ruby
assert_equal nil, nil
```

Minitest 5 issues a deprecation warning, and Minitest will fail
completely.

For additional context, the motivations and implications of this change
to Minitest have been discussed at length in [seattlerb/minitest#666][].

[seattlerb/minitest#666]: https://github.com/seattlerb/minitest/issues/666

Acronym inflections are stored with lowercase keys in the hash but
the match wasn't being lowercased before being looked up in the hash.
This shouldn't have any performance impact because before it would
fail to find the acronym and perform the `downcase` operation anyway.

Fixes #31052.

Fix french spelling mistake

Mirror the API of Ruby stdlib for #prev_day, #next_day, #prev_month, #next_month, #prev_year, #next_year

Trés -> Très 
https://fr.wiktionary.org/wiki/tr%C3%A8s

Remove unused require

Since f1828319, this file does not use methods added by `module/introspection`.

Explicitly pass window handle to `resize_window_to`

Unlike `resize_window`, `resize_window_to` has three arguments.
https://github.com/thoughtbot/capybara-webkit/blob/d63c3c8e3ae844f0c59359532a6dcb50f4a64d0a/lib/capybara/webkit/driver.rb#L135-L143

Therefore, if pass only width and height just like `resize_window`,
`ArgumentError`will be raised.
To prevent this, explicitly pass window handler.

Follow up of #31046

A relation includes `klass`, so it can not be used as it is if current
class is different from `current_scope.klass`. It should be created new
relation by current class to respect the klass and STI constraint.

Fixes #17603.
Fixes #23576.

This is partially fixed by e617fb57 when through association has already
loaded. Otherwise, second level through association should respect
`preload_scope`.

Fixes #30242.
Closes #30076.

[Ryuta Kamizono & CicholGricenchos]

If through association has already loaded, `source_type` is ignored to
loaded through records. The loaded records should be filtered by
`source_type` in that case.

Fixes #30904.

If a relation has eager-loading values, `count` and `exists?` works
properly, but `update_all` and `delete_all` doesn't work due to missing
`apply_join_dependency`. It should be applied to work consistently.

Fixes #28863.

Fixes #30315.

Generate the correct path in nested scaffold generator

Show `RequestForgeryProtection` methods in api doc  [ci skip]

Several methods of `RequestForgeryProtection` are not showed in the api
doc even though `:doc:` is specified.
(e.g. `form_authenticity_param`)
http://api.rubyonrails.org/classes/ActionController/RequestForgeryProtection.html

These methods are listed in the doc of v4.1.
http://api.rubyonrails.org/v4.1/classes/ActionController/RequestForgeryProtection.html

This is due to the influence of `:nodoc:` added in #18102, methods after
 `CROSS_ORIGIN_JAVASCRIPT_WARNING` not showed from the doc.
Therefore, in order to show the method like originally, added `startdoc`
after `CROSS_ORIGIN_JAVASCRIPT_WARNING`.

Currently, namespaced scaffold generator will generate an incorrect path
and the generated file will not work properly.

```
$ ./bin/rails g scaffold admin/user
$ ./bin/rails db:migrate
$  ./bin/rails t test/controllers
# Running:

E

Error:
Admin::UsersControllerTest#test_should_create_admin_user:
NameError: undefined local variable or method `admin_admin_users_url' for #<Admin::UsersControllerTest:0x000055a59f25ff68>
Did you mean?  admin_users
    test/controllers/admin/users_controller_test.rb:20:in `block (2 levels) in <class:UsersControllerTest>'
    test/controllers/admin/users_controller_test.rb:19:in `block in <class:UsersControllerTest>'

bin/rails test test/controllers/admin/users_controller_test.rb:18
```

This is because combine `controller_class_path` and `singular_table_name`
to generate route.
https://github.com/rails/rails/blob/360698aa245b45349d1d1b12e1afb34759515e69/railties/lib/rails/generators/named_base.rb#L172

Normally, if using namspaced generator, table name already contains
namespace. Therefore, adding `controller_class_path` adds extra namespace.
Since it is special only when explicitly specifying `model-name`, it is
modified to change the value only when `model-name`is specified.

Follow up of #30729

Fix Capybara::Webkit::Driver#resize_window deprecation warning

[ci skip] show the correct example to demonstrate inflections.

Improve docs of ActionDispatch::Routing::Mapper [ci skip]

Remove unused `calculate_rounded_number` and `digit_count`

These methods unused since 55336960.

  >[DEPRECATION] Capybara::Webkit::Driver#resize_window is
  deprecated. Please use Capybara::Window#resize_to instead.

This reverts commit 6f481e05, reversing
changes made to 592f790b.

In favor of #31039.

Fix guides build

We have already specified to install `bundler` 1.15.4 in `.travis.yml`.
https://github.com/rails/rails/blob/master/.travis.yml#L31..L32

However, `bundler` 1.16.0 may be used in the test.
https://travis-ci.org/rails/rails/jobs/296582467#L2208

The test failed due to this influence.
In order to avoid this, specifying `bundler` version in bug report
templates.

Remove unused classes

* `HasManyThroughCantDissociateNewRecords` and `HasManyThroughCantAssociateNewRecords`
are no longer used since f6b12c11.
* `ReadOnlyAssociation` is no longer used since 0da426be.

[ci skip]Fix typo in comments.

Fix "warning: instance variable @defined_root not initialized"

Currently, the following error is shows only when run the test using
`bin/test`.

```
./bin/test -w test/template/log_subscriber_test.rb
Run options: --seed 17167

# Running:

/rails/actionview/test/template/log_subscriber_test.rb:34: warning: instance variable @defined_root not initialized
```

In `AVLogSubscriberTest`, if the `Rails.root` is not defined, define the
method and undef it in teardown.
https://github.com/rails/rails/blob/master/actionview/test/template/log_subscriber_test.rb#L21..L33

However, in `bin/test`, `Rails.root` is defined, which results in referring to
uninitialized variables and warnings.

Ignore "gem "bundler" cannot be uninstalled because it is a default gem" error when tested with ruby-head