fix: Time::now() does not respect timezone when using setTestNow()

[kenjis]

Description

• fix bug

Checklist:

• Securely signed commits
• [] Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• [] User guide updated
• Conforms to style guide

[MGatner]

Time extends DateTime, not DateTimeImmutable, so it is mutable. In this case setTimezone is an internal method that returns a new instance, but I had to go look that up to be sure. I would still prefer to see this cloned for clarity, since the parent DateTime::setTimezone() would actually effect a change.

[kenjis]

CodeIgniter provides a fully-localized, immutable, date/time class that is built on PHP’s DateTime object, but uses the Intl extension’s features to convert times across timezones and display the output correctly for different locales. https://codeigniter4.github.io/CodeIgniter4/libraries/time.html

Time is immutable. If not, it is a bug. We should fix it.

[MGatner]

It is not. Any of the following methods will mutate the current object:

• __construct()
• add()
• modify()
• setDate()
• setISODate()
• setTime()
• setTimestamp()
• sub()

setTimezone() is an exception because we explicitly override the native method, but this is not apparent to a reviewer without looking at the class API.

[kenjis]

Oh, no! It is a big bug.

setTimestamp() is also overridden. But other methods are not.

[MGatner]

Time should have extended DateTimeImmutable if it was going to be immutable. Seems like a pretty big oversight there, but maybe immutability was added later to the User Guide? This all predates me.

For now I guess we change the User Guide? Changing the underlying class at this point seems to big a break. Alternatively we could override all the mutable methods but that could also be breaking and seems silly.

[kenjis]

It has been stated immutable since v4.0.0-alpha.1.

CodeIgniter provides a fully-localized, immutable, date/time class that is built on PHP's DateTime object, but uses the Intl extension's features to convert times across timezones and display the output correctly for different locales. This class is the Time class and lives in the CodeIgniter\I18n namespace.
https://github.com/codeigniter4/CodeIgniter4/blob/v4.0.0-alpha.1/user_guide_src/source/libraries/time.rst

[kenjis]

Even though it is a breaking change, but it seems we must fix it.
The current Time has methods of immutable and methods of mutable.
It is extremely bad design and difficult to use.

[kenjis]

For now I guess we change the User Guide?

It is not good. Because all methods implemented in Time are immutable.
I sent a PR for true immutable Time: #6771

[kenjis]

I fix this in 4.3 that Time is fully immutable.

[MGatner]

That took quite a detour 😅