Don't use Time Zone from a native value in RDF::Literal::Date, as Time Zone is optional and not included in ISO8601.

Fixes #447.

Author: gkellogg

lib/rdf/model/literal/date.rb

@@ -26,9 +26,7 @@ def initialize(value, datatype: nil, lexical: nil, **options)
           # Use midnight as midpoint of the interval
           ::DateTime.parse(value.strftime('%FT00:00:00'))
         when value.respond_to?(:to_datetime)
-          dt = value.to_datetime
-          @zone = dt.zone
-          dt
+          value.to_datetime
         else
           md = value.to_s.match(GRAMMAR)
           _, dt, tz = Array(md)

rdf.gemspec

@@ -29,21 +29,22 @@ Gem::Specification.new do |gem|
 
   gem.required_ruby_version      = '>= 3.0'
   gem.requirements               = []
-  gem.add_runtime_dependency     'link_header', '~> 0.0', '>= 0.0.8'
-  gem.add_runtime_dependency     'bcp47_spec',  '~> 0.2'
-  gem.add_runtime_dependency     'bigdecimal',  '~> 3.1', '>= 3.1.5'
-  gem.add_runtime_dependency     'ostruct',     '~> 0.6'
-  gem.add_development_dependency 'base64',      '~> 0.2'
-  gem.add_development_dependency 'rdf-spec',    '~> 3.3'
-  gem.add_development_dependency 'rdf-turtle',  '~> 3.3'
-  gem.add_development_dependency 'rdf-vocab',   '~> 3.3'
-  gem.add_development_dependency 'rdf-xsd',     '~> 3.3'
-  gem.add_development_dependency 'rest-client', '~> 2.1'
-  gem.add_development_dependency 'rspec',       '~> 3.13'
-  gem.add_development_dependency 'rspec-its',   '~> 1.3'
-  gem.add_development_dependency 'webmock',     '~> 3.23'
-  gem.add_development_dependency 'yard',        '~> 0.9'
-  gem.add_development_dependency 'faraday',     '~> 1.10'
+  gem.add_runtime_dependency     'bcp47_spec',         '~> 0.2'
+  gem.add_runtime_dependency     'bigdecimal',         '~> 3.1', '>= 3.1.5'
+  gem.add_runtime_dependency     'link_header',        '~> 0.0', '>= 0.0.8'
+  gem.add_runtime_dependency     'logger',             '~> 1.5'
+  gem.add_runtime_dependency     'ostruct',            '~> 0.6'
+  gem.add_development_dependency 'base64',             '~> 0.2'
+  gem.add_development_dependency 'rdf-spec',           '~> 3.3'
+  gem.add_development_dependency 'rdf-turtle',         '~> 3.3'
+  gem.add_development_dependency 'rdf-vocab',          '~> 3.3'
+  gem.add_development_dependency 'rdf-xsd',            '~> 3.3'
+  gem.add_development_dependency 'rest-client',        '~> 2.1'
+  gem.add_development_dependency 'rspec',              '~> 3.13'
+  gem.add_development_dependency 'rspec-its',          '~> 1.3'
+  gem.add_development_dependency 'webmock',            '~> 3.23'
+  gem.add_development_dependency 'yard',               '~> 0.9'
+  gem.add_development_dependency 'faraday',            '~> 1.10'
   gem.add_development_dependency 'faraday_middleware', '~> 1.2'
 
   gem.post_install_message       = nil

spec/model_literal_spec.rb

@@ -1178,7 +1178,7 @@ def self.literals(*selector)
       {
         ::Date.parse("2010-02-01")  => ["2010-02-01", "2010-02-01"],
         ::Date.parse("-2010-01-01") => ["-2010-01-01","-2010-01-01"],
-        ::DateTime.parse("2014-09-01T00:00:00-08:00") => ["2014-09-01-08:00", "2014-09-01Z"],
+        ::DateTime.parse("2014-09-01T00:00:00-08:00") => ["2014-09-01", "2014-09-01"],
       }.each do |obj, (str, canon)|
         it "to_str #{obj} to #{str.inspect}" do
           expect(described_class.new(obj).to_s).to eql str