New TimeZone should avoid explicit conversions

[jfelchner]

If the intention of the TimeZone cop is to keep people from accidentally working with a Time which has a Time Zone that they are not aware of, then explicit conversions via the utc method should be ignored since it doesn't matter what time zone Time.now returns if utc is chained onto it.

I can definitely see a situation where the user doesn't care what the Rails time zone is set to and they want to work explicitly with UTC times.

Proposal:

utc
localtime(offset)

should be marked as "safe" to use after Time.now and any other method marked as "dangerous" by this cop.

Rationale:

Time.now.utc while explicitly being cast to UTC, is not the same as Time.zone.now since Time.zone can be something other than UTC.

[bbatsov]

//cc @palkan

[palkan]

Just to make sure I understand you correctly:

# good
Time.now.utc
Time.parse(some_time).localtime("+09:00")

# still bad
Time.now.localtime

@bbatsov
Do you think we should add this as 'always' or 'acceptable' style? I think the second.

[ojab]

Second that, rubocop doesn't like Time.now.utc.strftime('%Y-%m-%d %H:%M:%S') here.

[jfelchner]

@palkan to keep it consistent with what you currently have, I'd just mark it as acceptable.