Use require_relative instead of require with full path

[bogdanvlviv]

@jeremy suggested converting require with a full path to require_relative. See #29176 (review)

After brief discuss with @fxn we decided to do it.

There are four cases i'm not sure about using require_relative:

• rails/activejob/test/support/integration/dummy_app_template.rb

  Line 8 in a625292

  require "#{File.expand_path("jobs_manager.rb", __dir__)}"

• rails/railties/lib/rails/app_loader.rb

  Line 45 in a625292

  require File.expand_path("../boot", APP_PATH)

• rails/activerecord/test/cases/migration_test.rb

  Lines 11 to 14 in a625292

  	require MIGRATIONS_ROOT + "/valid/2_we_need_reminders"
  	require MIGRATIONS_ROOT + "/rename/1_we_need_things"
  	require MIGRATIONS_ROOT + "/rename/2_rename_things"
  	require MIGRATIONS_ROOT + "/decimal/1_give_me_big_numbers"

• rails/railties/lib/rails/test_unit/test_requirer.rb

  Line 14 in a625292

  require File.expand_path(file)

Related to #29176

r? @fxn, @jeremy

[matthewd]

I don't like the redundancy introduced by some of these (ar_tests, COMPONENT_ROOT).

I think I also prefer the explicit ./ prefix that you're removing from some lines here, but that's just a minor preference.

[fxn]

I am fine with the changes.

ar_tests is the only one where I don't see quite the benefit. Also unsure about

require "cases/helper"

On the other hand COMPONENT_ROOT is a constant set as

COMPONENT_ROOT = File.expand_path("..", __dir__)

in the bin/test of every Rails component.

Regarding "./", I am totally for removing them because it is redundant. I never write leading dots in relative paths unless needed. For example, I do not write vim ./foo.rb, I always say vim foo.rb if foo.rb is in the current directory. When you do not have the cwd in $PATH then you use a leading dot to run an executable, but that is because it just does not work without it.

Summary, require_relative takes a path and resolves it relative to __dir__, the dot is adding no information there.

[rafaelfranca]

This one is clear to me, so I'd avoid change it

[bogdanvlviv]

I agree we should leave as it is.

[fxn]

Approved over here.

@bogdanvlviv can you rebase please?

[bogdanvlviv]

@fxn Done.

[fxn]

@rafaelfranca's feedback and mine are addressed (I saw that loading cases/helper is done that way in other places).

@matthewd are you cool with the patch?

[bogdanvlviv]

Thank you all for the review! ❤️