Extract default repository behavior into base class

lib/planet_express.rb

@@ -1,6 +1,9 @@
 # frozen_string_literal: true
 
 require 'planet_express/version'
+
+require 'planet_express/repository'
+
 require 'planet_express/shipping_option'
 require 'planet_express/shipping_option_repository'
 

lib/planet_express/repository.rb

@@ -0,0 +1,29 @@
+module PlanetExpress
+  class Repository
+    attr_reader :data
+
+    def initialize(data: )
+      @data = data
+    end
+
+   def all
+      data
+    end
+
+    def add(item)
+      data.push(item)
+    end
+
+    def remove(item)
+      data.delete(item)
+    end
+
+    def where(attribute_matchers = {})
+      all.select do |entry|
+        attribute_matchers.map do |attribute, value|
+          entry.public_send(attribute.to_sym) == value
+        end.all?
+      end
+    end
+  end
+end

lib/planet_express/shipping_option_repository.rb

@@ -1,24 +1,12 @@
 # frozen_string_literal: true
 
 module PlanetExpress
-  class ShippingOptionRepository
+  class ShippingOptionRepository < Repository
     attr_reader :data
     def initialize(data: nil)
       @data = data || default_data
     end
 
-    def all
-      data
-    end
-
-    def where(attribute_matchers = {})
-      all.select do |entry|
-        attribute_matchers.map do |attribute, value|
-          entry.public_send(attribute.to_sym) == value
-        end.all?
-      end
-    end
-
     def find_by_provider_and_package_size(provider, package_size)
       where(provider: provider, package_size: package_size).first
     end

spec/repository_spec.rb

@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+RSpec.describe PlanetExpress::Repository do
+  let!(:repository_item_class) { Struct.new(:test_attribute_a, :test_attribute_b) }
+
+  let(:repository_items) do
+    5.times.map do |i|
+      repository_item_class.new(i * 100, "Testing #{i}")
+    end
+  end
+
+  let!(:entries) { repository_items }
+
+  subject { described_class.new(data: entries) }
+
+
+  describe '#where' do
+    context 'no data' do
+      let(:entries) { [] }
+
+      it 'returns an empty array' do
+        expect(subject.where()).to eq([])
+      end
+    end
+
+    context 'no arguments' do
+      before(:each) do
+        expect(subject.all).to_not be_empty
+      end
+
+      it 'returns all items' do
+        expect(subject.where()).to eq(subject.all)
+      end
+    end
+
+    context 'with existing attribute' do
+      let(:expected_item) do
+        repository_item_class.new(150, 'Testing')
+      end
+
+      let(:entries) { repository_items + [expected_item]  }
+
+      it 'returns a list with the expected item' do
+        expect(subject.where(test_attribute_a: 150, test_attribute_b: "Testing")).to eq([expected_item])
+      end
+    end
+
+    context 'with unknown attribute' do
+      it 'throws an exception' do
+        expect do
+          subject.where(unknown_attribute: nil)
+        end.to raise_error(NoMethodError)
+      end
+    end
+  end
+
+  describe '#add' do
+    let(:item) { repository_item_class.new(152, 'Testing') }
+
+    it 'adds the item to the list' do
+      subject.add(item)
+
+      expect(subject.where(test_attribute_a: 152, test_attribute_b: 'Testing')).to eq([item])
+    end
+  end
+
+  describe '#remove' do
+    let(:item) { repository_item_class.new(153, 'Test') }
+
+    it 'removes the item from the list' do
+      subject.add(item)
+
+      expect { subject.remove(item) }
+        .to(change { subject.where(test_attribute_a: 153, test_attribute_b: 'Test') }.to([]))
+    end
+  end
+end

spec/shipping_option_repository_spec.rb

@@ -3,52 +3,6 @@
 RSpec.describe PlanetExpress::ShippingOptionRepository do
   subject { PlanetExpress::ShippingOptionRepository.new }
 
-  describe '#where' do
-    context 'no data' do
-      subject { PlanetExpress::ShippingOptionRepository.new(data: []) }
-
-      it 'returns an empty array' do
-        expect(subject.where()).to eq([])
-      end
-    end
-
-    context 'no arguments' do
-      before(:each) do
-        expect(subject.all).to_not be_empty
-      end
-
-      it 'returns all items' do
-        expect(subject.where()).to eq(subject.all)
-      end
-    end
-
-    context 'with existing attribute' do
-      let(:expected_item) do
-        build(:shipping_option, package_size: 'L', price_in_cents: 410)
-      end
-
-      let(:data) do
-        build_list(:shipping_option, 4, price_in_cents: 500) + [expected_item]
-      end
-
-      subject do
-        PlanetExpress::ShippingOptionRepository.new(data: data)
-      end
-
-      it 'returns a list with the expected item' do
-        expect(subject.where(package_size: 'L', price_in_cents: 410)).to eq([expected_item])
-      end
-    end
-
-    context 'with unknown attribute' do
-      it 'throws an exception' do
-        expect do
-          subject.where(unknown_attribute: nil)
-        end.to raise_error(NoMethodError)
-      end
-    end
-  end
-
   describe '#lowest_price_for_package_size' do
     it 'finds the lowest price for a package size' do
       expect(subject.lowest_price_for_package_size('L')).to eq(400)