add spec for DelegateAttribute module

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## [Unreleased]
 
 - remove `add_development_dependency` from gemspec
+- add spec for DelegateAttribute module
 
 ## [0.1.6] - 2024-01-14
 

lib/active_record_compose/delegate_attribute.rb

@@ -57,7 +57,7 @@ def delegate_attribute(*attributes, to:, **options)
     end
 
     def attributes
-      super.merge(delegated_attributes.to_h { [_1, public_send(_1)] })
+      (defined?(super) ? super : {}).merge(delegated_attributes.to_h { [_1, public_send(_1)] })
     end
   end
 end

spec/active_record_compose/delegate_attribute_spec.rb

@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'active_record_compose/delegate_attribute'
+
+RSpec.describe ActiveRecordCompose::DelegateAttribute do
+  before { stub_const('Dummy', klass) }
+
+  subject { klass.new(data) }
+
+  let(:data) { Struct.new(:x, :y, :z, keyword_init: true).new }
+
+  let(:klass) do
+    Class.new do
+      include ActiveRecordCompose::DelegateAttribute
+
+      def initialize(data)
+        @data = data
+      end
+
+      delegate_attribute :x, :y, to: :data
+
+      private
+
+      attr_reader :data
+    end
+  end
+
+  specify 'reader method must is defined' do
+    data.x = 'foo'
+    expect(data.x).to eq 'foo'
+    expect(subject.x).to eq 'foo'
+  end
+
+  specify 'writer method must is defined' do
+    subject.y = 'bar'
+    expect(data.y).to eq 'bar'
+    expect(subject.y).to eq 'bar'
+  end
+
+  specify 'definition declared in delegate must be included in attributes' do
+    subject.x = 'foo'
+    subject.y = 'bar'
+    expect(subject.attributes).to eq({ 'x' => 'foo', 'y' => 'bar' })
+  end
+end