New cop: Minitest/HooksGrouping

[fatkodima]

Or there is a better name for this cop.
It will check that setup/teardown are before all the test cases, and that setup is before teardown. It adds consistency and enforces the expectation of these methods to go first (to be easily noticeable/etc).

# bad
class SomethingTest < Minitest::Test
  def setup; end
  def test_something; end
  def teardown; end
end

# bad
class SomethingTest < Minitest::Test
  def teardown; end
  def setup; end
  def test_something; end
end

# good
class SomethingTest < Minitest::Test
  def setup; end
  def teardown; end
  def test_something; end
end

[koic]

Yeah, the naming is difficult too, there is a better name 😅 Anyway, I think it's worth opening up to the style guide first:
https://github.com/rubocop/minitest-style-guide

[tejasbubane]

Better name would be Minitest/HooksOrder similar to Style/RequireOrder, Style/KeywordParametersOrder, Rails/ActiveRecordCallbacksOrder, etc.

Additionally I think it should check for all hooks including the before and after methods:

# bad
class SomethingTest < Minitest::Test
  def after_teardown; end
  def before_teardown; end
  def setup; end
  def before_setup; end
  def after_setup; end
  def teardown; end
end

# good
class SomethingTest < Minitest::Test
  def before_setup; end
  def setup; end
  def after_setup; end
  def before_teardown; end
  def teardown; end
  def after_teardown; end
end