[Fix #67] TimeZone: Always autocorrect DateTime => Time

[vfonic]

This removes potential (and actual) bugs due to some methods not being present on DateTime class that are present on Time class.
If we always autocorrect to Time, we ensure the most appropriate correction.

#67
rubocop/rubocop#6930 (comment)

Sidenote: I believe a lot of problems here also comes from the tests that are a little bit hard to follow. The tests seem to have been written for code efficiency / lower line numbers. But they make it hard to understand which test refers to which of the two classes (Time or DateTime) and what exactly is being tested:

Why are "accepted methods" registering offenses:

      described_class::ACCEPTED_METHODS.each do |a_method|
        it "registers an offense #{klass}.now.#{a_method}" do
          inspect_source("#{klass}.now.#{a_method}")
          expect(cop.offenses.size).to eq(1)
          expect(cop.offenses.first.message).to include('`Time.zone.now`')
        end
      end

Etc.
If we decide to keep only one mode (as opposed to ['flexible', 'strict'], I believe the refactoring should start from the tests.

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[doloopwhile]

@vfonic
Should we do both of DateTime => Time and Time.now => Time.current be done is one Cop ?

They have different "stabilitiy".

• Time.now == Time.current in almost Rails projects (as long as developer do not override default configuration).
• Time.now != DateTime.now in all projects.

My suggestion is:

• To make Rails/TimeZone Cop to care only Time and to ignore DateTime
• And to create new Cop which warns usage of DateTime and replace DateTime => Time (Rails/DateTime ?)

[vfonic]

Should we do autocorrection DateTime => Time and autocorrection Time.now => Time.current be done is one Cop ?

My suggestion is:

Make Rails/TimeZone Cop to care only Time and ignore DateTime
and create new Cop which warns usage of DateTime and corrects DateTime => Time (Rails/DateTime ?)

🤔 This is a good question.
There are two "algorithms" for checking what needs to be changed. However, we are changing the same semantic ("make sure you use time with zone") in both cases.
I think it's better if we keep these together. (DateTime => Time and Time.now => Time.current)

• Time.now == Time.current in almost Rails projects (as long as developer do not override default configuration).

It's based on the machine's timezone. I understand most of production servers would have timezone in UTC, but do we really want to rely on that? That's why Time.now is not recommended. Also, using Time.now produces different results in production and development (time zone on my machine is not UTC).

I'll try to find the time to rewrite this cop, starting from what we want to have, in tests. (TDD ALL THE WAY!!! 😆)

What do you think?

[koic]

Make Rails/TimeZone Cop to care only Time and ignore DateTime

Yeah, Clould you please update it to ignore DateTime? DateTime is not mentioned in the Rails Style Guide and Rails/TimeZone cop's examples.

• https://rails.rubystyle.guide/#time-now
• https://docs.rubocop.org/projects/rails/en/stable/cops_rails/#railstimezone

Recently, #81 and #82 have been feedback. I think breaking by auto-correction should be fixed with the highest priority in this case.

I'm planning to release a patch version after the fix. Thank you for your consideration and discussion.

[vfonic]

I'm sorry I'm short on time lately. :(

I suggest we convert both DateTime and Time to Time methods that respect the timezone.
Feel free to take over.
Thanks!