Add support for ordinal date values in AS::TimeZone.iso8601

Date._iso8601 will attempt to parse certain args as ordinal dates eg. '21087' => 2021-03-28. Add ActiveSupport::TimeZone.iso8601 support for these
ordinal values to be consistent with Date._iso8601 and raise ArgumentError where the day of year is invalid.

Author: steventux

activesupport/CHANGELOG.md

@@ -1,3 +1,14 @@
+*   `TimeZone.iso8601` now accepts valid ordinal values similar to Ruby's `Date._iso8601` method.
+    A valid ordinal value will be converted to an instance of `TimeWithZone` using the `:year`
+    and `:yday` fragments returned from `Date._iso8601`.
+
+    ```ruby
+    twz = ActiveSupport::TimeZone["Eastern Time (US & Canada)"].iso8601("21087")
+    twz.to_a[0, 6] == [0, 0, 0, 28, 03, 2021]
+    ```
+
+    *Steve Laing*
+
 *   `Time#change` and methods that call it (eg. `Time#advance`) will now
     return a `Time` with the timezone argument provided, if the caller was
     initialized with a timezone argument.

activesupport/lib/active_support/values/time_zone.rb

@@ -387,10 +387,21 @@ def at(*args)
     def iso8601(str)
       parts = Date._iso8601(str)
 
+      year = parts.fetch(:year)
+
+      if parts.key?(:yday)
+        ordinal_date = Date.ordinal(year, parts.fetch(:yday))
+        month = ordinal_date.month
+        day = ordinal_date.day
+      else
+        month = parts.fetch(:mon)
+        day = parts.fetch(:mday)
+      end
+
       time = Time.new(
-        parts.fetch(:year),
-        parts.fetch(:mon),
-        parts.fetch(:mday),
+        year,
+        month,
+        day,
         parts.fetch(:hour, 0),
         parts.fetch(:min, 0),
         parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0),
@@ -403,7 +414,7 @@ def iso8601(str)
         TimeWithZone.new(nil, self, time)
       end
 
-    rescue KeyError
+    rescue Date::Error, KeyError
       raise ArgumentError, "invalid date"
     end
 

activesupport/test/time_zone_test.rb

@@ -365,11 +365,19 @@ def test_iso8601_with_ambiguous_time
     assert_equal Time.utc(2014, 10, 25, 22, 0, 0), zone.parse("2014-10-26T01:00:00")
   end
 
-  def test_iso8601_with_invalid_value_parseable_by_date__iso8601
+  def test_iso8601_with_ordinal_date_value
+    zone = ActiveSupport::TimeZone["Eastern Time (US & Canada)"]
+
+    twz = zone.iso8601("21087")
+    assert_equal Time.utc(2021, 3, 28, 0, 0, 0), twz.time
+    assert_equal zone, twz.time_zone
+  end
+
+  def test_iso8601_with_invalid_ordinal_date_value
     zone = ActiveSupport::TimeZone["Eastern Time (US & Canada)"]
 
     exception = assert_raises(ArgumentError) do
-      zone.iso8601("12936")
+      zone.iso8601("21367")
     end
 
     assert_equal "invalid date", exception.message