Format Time#inspect with Internet Extended Date/Time Format (#16039)

The Internet Extended Date/Time Format (IXDTF) as described in [RFC 9557] is a standard for representing a timestamp together with zone information.

Changes to the format:
* Replace `UTC` location by `Z` offset
* Skip zero nanoseconds entirely even when `with_nanoseconds` is true (see #16039 (comment))
* Remove whitespace between time and offset
* Wrap location in square brackets to indicate an IXDTF time-zone suffix

[RFC 9557]: https://datatracker.ietf.org/doc/html/rfc9557

Co-authored-by: Julien Portalier <[email protected]>

Author: straight-shoota

spec/std/time/time_spec.cr

@@ -651,18 +651,18 @@ describe Time do
   end
 
   it "#inspect" do
-    Time.utc(2014, 1, 2, 3, 4, 5).inspect.should eq "2014-01-02 03:04:05.0 UTC"
-    Time.utc(2014, 1, 2, 3, 4, 5, nanosecond: 123_456_789).inspect.should eq "2014-01-02 03:04:05.123456789 UTC"
+    Time.utc(2014, 1, 2, 3, 4, 5).inspect.should eq "2014-01-02 03:04:05Z"
+    Time.utc(2014, 1, 2, 3, 4, 5, nanosecond: 123_456_789).inspect.should eq "2014-01-02 03:04:05.123456789Z"
 
     with_zoneinfo do
       location = Time::Location.load("Europe/Berlin")
-      Time.local(2014, 1, 2, 3, 4, 5, location: location).inspect.should eq "2014-01-02 03:04:05.0 +01:00 Europe/Berlin"
-      Time.local(2014, 1, 2, 3, 4, 5, nanosecond: 123_456_789, location: location).inspect.should eq "2014-01-02 03:04:05.123456789 +01:00 Europe/Berlin"
+      Time.local(2014, 1, 2, 3, 4, 5, location: location).inspect.should eq "2014-01-02 03:04:05+01:00[Europe/Berlin]"
+      Time.local(2014, 1, 2, 3, 4, 5, nanosecond: 123_456_789, location: location).inspect.should eq "2014-01-02 03:04:05.123456789+01:00[Europe/Berlin]"
     end
 
     location = Time::Location.fixed(3601)
-    Time.local(2014, 1, 2, 3, 4, 5, location: location).inspect.should eq "2014-01-02 03:04:05.0 +01:00:01"
-    Time.local(2014, 1, 2, 3, 4, 5, nanosecond: 123_456_789, location: location).inspect.should eq "2014-01-02 03:04:05.123456789 +01:00:01"
+    Time.local(2014, 1, 2, 3, 4, 5, location: location).inspect.should eq "2014-01-02 03:04:05+01:00:01"
+    Time.local(2014, 1, 2, 3, 4, 5, nanosecond: 123_456_789, location: location).inspect.should eq "2014-01-02 03:04:05.123456789+01:00:01"
   end
 
   it "at methods" do

src/file.cr

@@ -40,7 +40,7 @@ require "crystal/system/file"
 # tempfile = File.tempfile("foo")
 #
 # File.size(tempfile.path)                   # => 6
-# File.info(tempfile.path).modification_time # => 2015-10-20 13:11:12 UTC
+# File.info(tempfile.path).modification_time # => 2015-10-20 13:11:12Z
 # File.exists?(tempfile.path)                # => true
 # File.read_lines(tempfile.path)             # => ["foobar"]
 # ```
@@ -208,7 +208,7 @@ class File < IO::FileDescriptor
   # ```
   # File.write("foo", "foo")
   # File.info("foo").size              # => 3
-  # File.info("foo").modification_time # => 2015-09-23 06:24:19 UTC
+  # File.info("foo").modification_time # => 2015-09-23 06:24:19Z
   #
   # File.symlink("foo", "bar")
   # File.info("bar", follow_symlinks: false).type.symlink? # => true

src/http/common.cr

@@ -343,9 +343,9 @@ module HTTP
   # ```
   # require "http"
   #
-  # HTTP.parse_time("Sun, 14 Feb 2016 21:00:00 GMT")  # => "2016-02-14 21:00:00 UTC"
-  # HTTP.parse_time("Sunday, 14-Feb-16 21:00:00 GMT") # => "2016-02-14 21:00:00 UTC"
-  # HTTP.parse_time("Sun Feb 14 21:00:00 2016")       # => "2016-02-14 21:00:00 UTC"
+  # HTTP.parse_time("Sun, 14 Feb 2016 21:00:00 GMT")  # => "2016-02-14 21:00:00Z"
+  # HTTP.parse_time("Sunday, 14-Feb-16 21:00:00 GMT") # => "2016-02-14 21:00:00Z"
+  # HTTP.parse_time("Sun Feb 14 21:00:00 2016")       # => "2016-02-14 21:00:00Z"
   # ```
   #
   # Uses `Time::Format::HTTP_DATE` as parser.

src/json/to_json.cr

@@ -310,7 +310,7 @@ end
 # end
 #
 # timestamp = TimestampArray.from_json(%({"dates":[1459859781,1567628762]}))
-# timestamp.dates   # => [2016-04-05 12:36:21 UTC, 2019-09-04 20:26:02 UTC]
+# timestamp.dates   # => [2016-04-05 12:36:21Z, 2019-09-04 20:26:02Z]
 # timestamp.to_json # => %({"dates":[1459859781,1567628762]})
 # ```
 #
@@ -328,7 +328,7 @@ end
 # end
 #
 # timestamp = TimestampArray.from_json(%({"dates":["Apr 5, 2016","Sep 4, 2019"]}))
-# timestamp.dates   # => [2016-04-05 00:00:00 UTC, 2019-09-04 00:00:00 UTC]
+# timestamp.dates   # => [2016-04-05 00:00:00Z, 2019-09-04 00:00:00Z]
 # timestamp.to_json # => %({"dates":["Apr 5, 2016","Sep 4, 2019"]})
 # ```
 #
@@ -371,7 +371,7 @@ end
 # end
 #
 # timestamp = TimestampHash.from_json(%({"birthdays":{"foo":1459859781,"bar":1567628762}}))
-# timestamp.birthdays # => {"foo" => 2016-04-05 12:36:21 UTC, "bar" => 2019-09-04 20:26:02 UTC}
+# timestamp.birthdays # => {"foo" => 2016-04-05 12:36:21Z, "bar" => 2019-09-04 20:26:02Z}
 # timestamp.to_json   # => %({"birthdays":{"foo":1459859781,"bar":1567628762}})
 # ```
 #
@@ -389,7 +389,7 @@ end
 # end
 #
 # timestamp = TimestampHash.from_json(%({"birthdays":{"foo":"Apr 5, 2016","bar":"Sep 4, 2019"}}))
-# timestamp.birthdays # => {"foo" => 2016-04-05 00:00:00 UTC, "bar" => 2019-09-04 00:00:00 UTC}
+# timestamp.birthdays # => {"foo" => 2016-04-05 00:00:00Z, "bar" => 2019-09-04 00:00:00Z}
 # timestamp.to_json   # => %({"birthdays":{"foo":"Apr 5, 2016","bar":"Sep 4, 2019"}})
 # ```
 #
@@ -435,7 +435,7 @@ end
 # end
 #
 # person = Person.from_json(%({"birth_date": 1459859781}))
-# person.birth_date # => 2016-04-05 12:36:21 UTC
+# person.birth_date # => 2016-04-05 12:36:21Z
 # person.to_json    # => %({"birth_date":1459859781})
 # ```
 module Time::EpochConverter
@@ -459,7 +459,7 @@ end
 # end
 #
 # timestamp = Timestamp.from_json(%({"value": 1459860483856}))
-# timestamp.value   # => 2016-04-05 12:48:03.856 UTC
+# timestamp.value   # => 2016-04-05 12:48:03.856Z
 # timestamp.to_json # => %({"value":1459860483856})
 # ```
 module Time::EpochMillisConverter