Create attributes concern

lib/kangaru/concerns/attributes_concern.rb

@@ -0,0 +1,21 @@
+module Kangaru
+  module Concerns
+    module AttributesConcern
+      extend Concern
+
+      class_methods do
+        def attributes
+          instance_methods.grep(/\w=$/).map do |attribute|
+            attribute.to_s.delete_suffix("=").to_sym
+          end
+        end
+      end
+
+      def initialize(**attributes)
+        attributes.slice(*self.class.attributes).each do |attr, value|
+          instance_variable_set(:"@#{attr}", value)
+        end
+      end
+    end
+  end
+end

sig/kangaru/concerns/attributes_concern.rbs

@@ -0,0 +1,17 @@
+module Kangaru
+  module Concerns
+    module AttributesConcern
+      extend Concern
+
+      module ClassMethods
+        def attributes: -> Array[Symbol]
+      end
+
+      extend ClassMethods
+
+      def instance_methods: -> Array[Symbol]
+
+      def initialize: (**untyped) -> void
+    end
+  end
+end

spec/kangaru/concerns/attributes_concern_spec.rb

@@ -0,0 +1,97 @@
+RSpec.describe Kangaru::Concerns::AttributesConcern do
+  subject(:model) { model_class.new(**attributes) }
+
+  let(:model_class) do
+    Class.new { include Kangaru::Concerns::AttributesConcern }
+  end
+
+  describe "#initialize" do
+    context "when concern has not defined any attr_accessors" do
+      context "and no attributes are given" do
+        let(:attributes) { {} }
+
+        it "does not raise any errors" do
+          expect { model }.not_to raise_error
+        end
+
+        it "does not set any instance variables" do
+          expect { model }.not_to change { model_class.instance_variables }
+        end
+      end
+
+      context "and attributes are given" do
+        let(:attributes) { { foo: "foo", bar: "bar" } }
+
+        it "does not raise any errors" do
+          expect { model }.not_to raise_error
+        end
+
+        it "does not set the attributes" do
+          expect(model).not_to respond_to(*attributes.keys)
+        end
+      end
+    end
+
+    context "when concern has defined attr_accessors" do
+      let(:model_class) do
+        Class.new do
+          include Kangaru::Concerns::AttributesConcern
+
+          attr_accessor :foo, :bar, :baz
+        end
+      end
+
+      context "and no attributes are given" do
+        let(:attributes) { {} }
+
+        it "does not raise any errors" do
+          expect { model }.not_to raise_error
+        end
+      end
+
+      context "and attributes are given" do
+        let(:attributes) { { foo: "foo", bar: "bar" } }
+
+        it "does not raise any errors" do
+          expect { model }.not_to raise_error
+        end
+
+        it "sets the attributes" do
+          expect(model).to have_attributes(**attributes)
+        end
+      end
+    end
+  end
+
+  describe ".attributes" do
+    subject(:attributes) { model_class.attributes }
+
+    context "when no attr_accessors are set" do
+      it "does not raise any errors" do
+        expect { attributes }.not_to raise_error
+      end
+
+      it "returns an empty array" do
+        expect(attributes).to be_empty
+      end
+    end
+
+    context "when attr_accessors are set" do
+      let(:model_class) do
+        Class.new do
+          include Kangaru::Concerns::AttributesConcern
+
+          attr_accessor :foo, :bar, :baz
+        end
+      end
+
+      it "does not raise any errors" do
+        expect { attributes }.not_to raise_error
+      end
+
+      it "returns the expected attributes" do
+        expect(attributes).to contain_exactly(:foo, :bar, :baz)
+      end
+    end
+  end
+end