Cleanup loaded features and constants after dependency tests.
Explicit route test class

shows the class that the test must extend in order to have the assert_routing method available
Fix that a collection proxy could be cached before the save of the owner, resulting in an invalid proxy lacking the owner’s id.

Absent this fix calls like: owner.association.update_all to behave unexpectedly because they try to act on association objects where
owner_id is null.

more evidence here: https://gist.github.com/Empact/5865555
```
Active Record 3.2.13
-- create_table(:firms, {:force=>true})
   -> 0.1371s
-- create_table(:clients, {:force=>true})
   -> 0.0005s
1 clients. 1 expected.
1 clients updated. 1 expected.
```

```
Active Record 4.0.0
-- create_table(:firms, {:force=>true})
   -> 0.1606s
-- create_table(:clients, {:force=>true})
   -> 0.0004s
1 clients. 1 expected.
0 clients updated. 1 expected.
```
FileHandler should not be called for files outside the root

FileHandler#matches? should return false for files that are outside the
"root" path.
AR::UnknownAttributeError should include the class name of a record

This would be helpful if 2 models have an attribute that has a similar
name to the other. e.g:

before:

    User.new(name: "Yuki Nishijima", projects_attributes: [name: "kaminari"])
    # => ActiveRecord::UnknownAttributeError: unknown attribute: name

after:

    User.new(name: "Yuki Nishijima", projects_attributes: [name: "kaminari"])
    # => ActiveRecord::UnknownAttributeError: unknown attribute on User: name
Use include_blank value as option label

Update select_tag to reflect documentation and behave the same as form builder select. If the value of include_blank is not boolean true, use that value as the option label.
Enable emitting of warnings from ActiveJob tests.
- Removed unused variable warnings from ActiveJob Adapters
[ci skip] merge docs
[ci skip] Make merge method nodoc
Mention `perform_now` in AJ base docs to specify how to immediately invoke a job.    [ci skip]
Merge branch 'activerecord-merge-docs' of https://github.com/justanshulsharma/rails into justanshulsharma-activerecord-merge-docs
Merge branch 'justanshulsharma-activerecord-merge-docs'
AR::UnknownAttributeError should include the class name of a record

This would be helpful if 2 models have an attribute that has a similar
name to the other. e.g:

before:

    User.new(name: "Yuki Nishijima", projects_attributes: [name: "kaminari"])
    # => ActiveRecord::UnknownAttributeError: unknown attribute: name

after:

    User.new(name: "Yuki Nishijima", projects_attributes: [name: "kaminari"])
    # => ActiveRecord::UnknownAttributeError: unknown attribute on User: name
Merge pull request #17019 from yuki24/add-class-name-to-unknown-attr-error

Message on AR::UnknownAttributeError should include the class name of a record
Merge pull request #17324 from vipulnsward/activejob-warnings

Enable emitting of warnings from ActiveJob tests.
docs, It's "Active Job" not "Active job". [ci skip]
Merge pull request #17329 from vipulnsward/mention-perform-later-docs

Mention `perform_now` in AJ base docs to specify how to immediately invoke a job [ci skip]
No need to specify log level, run at log level as all other Rails components.
- Remove duplication in AJ logging test for setting logger.
- Remove un-needed require in AJ rescue test.