The name of the minitest library is spelled that way: regular font, and
lowercase. Lowercase is used even at the beginning of sentences, see

    http://docs.seattlerb.org/minitest/

I double-checked this with @zenspider too (thanks!).

Fix zero-byte files upload in #33630

Clarify changelog entry added in #33779 [ci skip]

Skip delivery notification when perform_deliveries is false.

* Use utf8mb4 character set by default

`utf8mb4` character set supports supplementary characters including emoji.
`utf8` character set with 3-Byte encoding is not enough to support them.

There was a downside of 4-Byte length character set with MySQL 5.5 and 5.6:

"ERROR 1071 (42000): Specified key was too long; max key length is 767 bytes"
for Rails string data type which is mapped to varchar(255) type.

MySQL 5.7 supports 3072 byte key prefix length by default.

* Remove `DEFAULT COLLATE` from Active Record unit test databases

There should be no "one size fits all" collation in MySQL 5.7.
Let MySQL server choose the default collation for Active Record
unit test databases.

Users can choose their best collation for their databases
by setting `options[:collation]` based on their requirements.

* InnoDB FULLTEXT indexes support since MySQL 5.6
it does not have to use MyISAM storage engine whose maximum key length is 1000 bytes.
Using MyISAM storag engine with utf8mb4 character set would cause
"Specified key was too long; max key length is 1000 bytes"

https://dev.mysql.com/doc/refman/5.6/en/innodb-fulltext-index.html

* References

"10.9.1 The utf8mb4 Character Set (4-Byte UTF-8 Unicode Encoding)"
https://dev.mysql.com/doc/refman/5.7/en/charset-unicode-utf8mb4.html

"10.9.2 The utf8mb3 Character Set (3-Byte UTF-8 Unicode Encoding)"
https://dev.mysql.com/doc/refman/5.7/en/charset-unicode-utf8.html

"14.8.1.7 Limits on InnoDB Tables"
https://dev.mysql.com/doc/refman/5.7/en/innodb-restrictions.html
> If innodb_large_prefix is enabled (the default), the index key prefix limit is 3072 bytes
> for InnoDB tables that use DYNAMIC or COMPRESSED row format.

* CI against MySQL 5.7

Followed this instruction and changed root password to empty string.
https://docs.travis-ci.com/user/database-setup/#MySQL-57

* The recommended minimum version of MySQL is 5.7.9
to support utf8mb4 character set and `innodb_default_row_format`

MySQL 5.7.9 introduces `innodb_default_row_format` to support 3072 byte length index by default.
Users do not have to change MySQL database configuration to support Rails string type.

https://dev.mysql.com/doc/refman/5.7/en/innodb-parameters.html#sysvar_innodb_default_row_format

https://dev.mysql.com/doc/refman/5.7/en/innodb-restrictions.html
> If innodb_large_prefix is enabled (the default),
> the index key prefix limit is 3072 bytes for InnoDB tables that use DYNAMIC or COMPRESSED row format.

* The recommended minimum version of MariaDB is 10.2.2
MariaDB 10.2.2 is the first version of MariaDB supporting `innodb_default_row_format`
Also MariaDB says "MySQL 5.7 is compatible with MariaDB 10.2".

- innodb_default_row_format
https://mariadb.com/kb/en/library/xtradbinnodb-server-system-variables/#innodb_default_row_format

- "MariaDB versus MySQL - Compatibility"
https://mariadb.com/kb/en/library/mariadb-vs-mysql-compatibility/
> MySQL 5.7 is compatible with MariaDB 10.2

- "Supported Character Sets and Collations"
https://mariadb.com/kb/en/library/supported-character-sets-and-collations/

Pushing scope attributes was added at d4007d5a for fixing inheritance
object creation. But it was not a better fix, since we could just pull
that on demand in `Inheritance` module.

I'd like to use this `scoping` handling on klass level to address
unwanted internal scoping issues.

`scoping` stashes the reciever and then returning that as `klass.all`.
`all.scoping` has no effect to the public behavior, so it is redundant.

The `existing` arg was added at 8bc0fce0, but it is no longer used since
aac9da25.

Make sure there are no duplicated nested records with create_with

In order to avoid double assignments of nested_attributes for `has_many`
relations during record initialization, nested_attributes in `create_with`
should not be passed into `klass.new` and have them populate during
`initialize_internals_callback` with scope attributes.

However, `create_with` keys should always have precedence over where
clauses, so if there are same keys in both `create_with` and
`where_values_hash`, the value in `create_with` should be the one that's
used.

Follow up of 3e814907.

Followup to a recently merged PR, too minor and detailed to require a
modification to the contributed patch.

ActiveJob Backburner adapter: fix priority

Add #unfreeze_time to ActiveSupport::Testing::TimeHelpers

docs: Fix typo in activerecord/CHANGELOG.md

[ci skip]

retry_on argument `attempts` clarification

Follow up #33637 and #33770

Since #33770 `#configs_for` changed method signature and it isn't
supposed to work with a passed block.

See `ConnectionUrlResolver#database_from_path` in
 `activerecord/lib/active_record/connection_adapters/connection_specification.rb`

Without `perform_enqueued_jobs`, job are not executed and assertion is not done.

The writer was added during Arel refactoring to pass Active Record
tests at 7a29220c.
That is no longer used since 846832ae.

Rather than a configuration on the connection.

The priority wasn't being passed from ActiveJob to Backburner, despite
priority being supported. This also brings it inline with the docs,
which mark Backburner as supporting priorities in the "Backend Features"
table: https://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html

Don’t allocate array on no args

When no dependencies are present to be digested there is no reason to build an array just to turn around and turn it back into a string.

The dependencies array is not mutated in this method so we can use the same empty array across all invocations.

Total allocated: 791402 bytes (7294 objects)
Total allocated: 777442 bytes (7132 objects)

(791402 - 777442) / 791402.0 # => 1.76 % speed improvement

Closes #32885.

Fix non_numeric_string?