Treat an empty one/other plural form as missing, not as content

`build_pot_entry` guarded with `.nil?`, but an empty-string form is truthy
in Ruby, so `var_dict['one'] || var_dict['other']` returned `''` for an
empty `one` and produced an entry with an empty `msgid` — which gettext
folds into the header, silently dropping the entry from the `.pot`.

Extract `msgid_for` (the `one`-or-`other` choice), shared by the forward
and reverse paths so the written `msgid` always matches the one looked up
later, and treat an empty `one` like an absent one (fall back to `other`).
The required-form guard now rejects empty strings too, so an empty `other`
fails with the existing clear error instead of emitting a broken entry.

Author: jkmassel

lib/fastlane/plugin/wpmreleasetoolkit/helper/ios/ios_stringsdict_helper.rb

@@ -206,12 +206,22 @@ def self.context_for(key:, variable:, single_variable:)
           single_variable ? key : "#{key}:#{variable}"
         end
 
+        # The English string that becomes a variable's gettext `msgid`: the `one`
+        # form when it has content, otherwise `other`. Forward and reverse both
+        # use this, so the `msgid` written to the `.pot` matches the one later
+        # looked up in the translated `.po` — and an empty `one` no longer yields
+        # an empty `msgid` (which gettext drops, silently losing the entry).
+        def self.msgid_for(var_dict)
+          one = var_dict['one']
+          one.nil? || one.empty? ? var_dict['other'] : one
+        end
+
         def self.build_pot_entry(context:, var_dict:, key:, variable:)
-          singular = var_dict['one'] || var_dict['other']
+          singular = msgid_for(var_dict)
           plural = var_dict['other']
-          if singular.nil? || plural.nil?
+          if singular.nil? || singular.empty? || plural.nil? || plural.empty?
             UI.user_error!("Stringsdict entry '#{key}' is missing a required plural form " \
-                           "(needs at least 'other'; 'one' recommended for the singular).")
+                           "(needs a non-empty 'other'; 'one' recommended for the singular).")
           end
 
           warn_dropped_categories(key: key, variable: variable, var_dict: var_dict)
@@ -247,8 +257,7 @@ def self.warn_dropped_categories(key:, variable:, var_dict:)
 
         # The translated plural forms for a context, or `[]` if untranslated.
         def self.translated_forms(parsed_po:, context:, source_var:)
-          msgid = source_var['one'] || source_var['other']
-          entry = parsed_po[context, msgid]
+          entry = parsed_po[context, msgid_for(source_var)]
           return [] if entry.nil? || entry.msgstr.nil?
 
           forms = entry.msgstr.split(PLURAL_SEPARATOR, -1)

spec/ios_stringsdict_helper_spec.rb

@@ -182,6 +182,42 @@ def convert_po_to_stringsdict(po_content, template:, locale:)
         expect(content).not_to include('No homes found')
       end
     end
+
+    it 'treats an empty `one` as absent — uses `other` as the singular rather than dropping the entry' do
+      in_tmp_dir do |dir|
+        src = File.join(dir, 'empty-one.stringsdict')
+        described_class.write(
+          data: {
+            'k' => {
+              'NSStringLocalizedFormatKey' => '%#@c@',
+              'c' => { 'NSStringFormatSpecTypeKey' => 'NSStringPluralRuleType', 'one' => '', 'other' => '%d items' }
+            }
+          },
+          path: src
+        )
+        pot = File.join(dir, 'out.pot')
+        count = described_class.generate_pot(stringsdict_paths: src, output_path: pot)
+        expect(count).to eq(1) # entry is emitted, not silently dropped via an empty msgid
+        expect(File.read(pot)).to include('msgid "%d items"') # `other` becomes the msgid
+      end
+    end
+
+    it 'raises when `other` is empty (an empty form counts as missing)' do
+      in_tmp_dir do |dir|
+        src = File.join(dir, 'empty-other.stringsdict')
+        described_class.write(
+          data: {
+            'k' => {
+              'NSStringLocalizedFormatKey' => '%#@c@',
+              'c' => { 'NSStringFormatSpecTypeKey' => 'NSStringPluralRuleType', 'one' => '%d item', 'other' => '' }
+            }
+          },
+          path: src
+        )
+        expect { described_class.generate_pot(stringsdict_paths: src, output_path: File.join(dir, 'o.pot')) }
+          .to raise_error(FastlaneCore::Interface::FastlaneError, /missing a required plural form/)
+      end
+    end
   end
 
   describe '.generate_stringsdict_from_po' do