Always treat dates as Ruby Date objects.

If the date in the YAML is quoted, e.g., `"2023-06-24"`, then the Ruby YAML
parser - quite reasonably - assumed that they *must* be strings, so does not
parse them into Ruby Date objects.

We always want certain fields to be treated as Date objects, so this commit
ensures that those fields always return a Date object, or `''` if the date
is invalid or empty.

Fixes #122.

lib/cff/formatters/formatter.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-# Copyright (c) 2018-2022 The Ruby Citation File Format Developers.
+# Copyright (c) 2018-2023 The Ruby Citation File Format Developers.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -67,16 +67,9 @@ def self.month_and_year_from_model(model) # rubocop:disable Metrics
       end
 
       def self.month_and_year_from_date(value)
-        if value.is_a?(Date)
-          [value.month, value.year].map(&:to_s)
-        else
-          begin
-            date = Date.parse(value.to_s)
-            [date.month, date.year].map(&:to_s)
-          rescue ArgumentError
-            ['', '']
-          end
-        end
+        return ['', ''] unless value.is_a?(Date)
+
+        [value.month, value.year].map(&:to_s)
       end
 
       # CFF 'pages' is the number of pages, which has no equivalent in BibTeX

lib/cff/model_part.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-# Copyright (c) 2018-2022 The Ruby Citation File Format Developers.
+# Copyright (c) 2018-2023 The Ruby Citation File Format Developers.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -59,23 +59,57 @@ def self.attr_date(*symbols) # :nodoc:
       symbols.each do |symbol|
         field = symbol.to_s.tr('_', '-')
 
-        class_eval(
-          # def date_end=(date)
-          #   date = (date.is_a?(Date) ? date.dup : Date.parse(date))
-          #
-          #   @fields['date-end'] = date
-          # end
-          <<-END_SETTER, __FILE__, __LINE__ + 1
-            def #{symbol}=(date)
-              date = (date.is_a?(Date) ? date.dup : Date.parse(date))
-
-              @fields['#{field}'] = date
-            end
-          END_SETTER
-        )
+        date_getter(symbol, field)
+        date_setter(symbol, field)
       end
     end
 
+    def self.date_getter(symbol, field)
+      class_eval(
+        # def date_end
+        #   date = @fields['date-end']
+        #   return date if date.is_a?(Date)
+        #
+        #   begin
+        #     Date.parse(date)
+        #   rescue
+        #     ''
+        #   end
+        # end
+        <<-END_GETTER, __FILE__, __LINE__ + 1
+          def #{symbol}
+            date = @fields['#{field}']
+            return date if date.is_a?(Date)
+
+            begin
+              Date.parse(date)
+            rescue
+              ''
+            end
+          end
+        END_GETTER
+      )
+    end
+
+    def self.date_setter(symbol, field)
+      class_eval(
+        # def date_end=(date)
+        #   date = (date.is_a?(Date) ? date.dup : Date.parse(date))
+        #
+        #   @fields['date-end'] = date
+        # end
+        <<-END_SETTER, __FILE__, __LINE__ + 1
+          def #{symbol}=(date)
+            date = (date.is_a?(Date) ? date.dup : Date.parse(date))
+
+            @fields['#{field}'] = date
+          end
+        END_SETTER
+      )
+    end
+
+    private_class_method :date_getter, :date_setter
+
     private
 
     def method_to_field(name)

test/formatters/formatter_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-# Copyright (c) 2018-2022 The Ruby Citation File Format Developers.
+# Copyright (c) 2018-2023 The Ruby Citation File Format Developers.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -25,13 +25,9 @@ def test_month_and_year_from_date
       assert_equal(['', ''], CFF::Formatters::Formatter.month_and_year_from_date(date))
     end
 
-    date_str = '2021-08-05'
-    date = Date.parse(date_str)
     assert_equal(
-      ['8', '2021'], CFF::Formatters::Formatter.month_and_year_from_date(date_str)
-    )
-    assert_equal(
-      ['8', '2021'], CFF::Formatters::Formatter.month_and_year_from_date(date)
+      ['8', '2021'],
+      CFF::Formatters::Formatter.month_and_year_from_date(Date.parse('2021-08-05'))
     )
   end