Add tests for a subclass redefining a parent class' key

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: dblock

spec/ruby-enum/enum_spec.rb

@@ -27,6 +27,10 @@ class OtherSecondSubclass < FirstSubclass
   class SubclassWithNoOwnDefines < Colors
   end
 
+  class SubclassRedefiningParentKey < Colors
+    define :RED, 'crimson'
+  end
+
   it 'returns an enum value' do
     expect(Colors::RED).to eq 'red'
     expect(Colors::GREEN).to eq 'green'
@@ -414,6 +418,37 @@ class EmptyEnums
         expect(SubclassWithNoOwnDefines.each.map { |key, _enum| key }).to eq(%i[RED GREEN])
       end
     end
+
+    context 'when a subclass redefines a key already used by a parent class' do
+      it 'does not raise a duplicate key error' do
+        expect(SubclassRedefiningParentKey::RED).to eq 'crimson'
+      end
+
+      it "the subclass' own value takes precedence" do
+        expect(SubclassRedefiningParentKey.value(:RED)).to eq 'crimson'
+      end
+
+      it "the subclass' own value is used in to_h" do
+        expect(SubclassRedefiningParentKey.to_h).to eq(RED: 'crimson', GREEN: 'green')
+      end
+
+      it 'includes both the parent and its own redefined value in values' do
+        expect(SubclassRedefiningParentKey.values).to eq(%w[red green crimson])
+      end
+
+      it "the parent class' own value is unaffected" do
+        expect(Colors::RED).to eq 'red'
+        expect(Colors.value(:RED)).to eq 'red'
+      end
+
+      it 'still allows the parent class to raise a duplicate key error for its own re-definitions' do
+        expect do
+          Colors.class_eval do
+            define :RED, 'red'
+          end
+        end.to raise_error Ruby::Enum::Errors::DuplicateKeyError, /RED/
+      end
+    end
   end
 
   describe 'default value' do