testing Cart with mocked out Products

spec/models/cart_spec.rb

@@ -0,0 +1,38 @@
+require 'spec_helper'
+
+describe Cart do
+
+  context 'with unique products' do
+    before(:each) do
+      @book1 = mock_model(Product, :price => 1)
+      @book2 = mock_model(Product, :price => 2)
+      @cart = Cart.new
+      @cart.add_product @book1
+      @cart.add_product @book2
+    end
+    it 'should report two items in cart' do
+      @cart.items.size.should == 2
+      @cart.total_items.should == 2
+    end
+    it 'should sum prices of both items in cart' do
+      @cart.total_price.should == 3
+    end
+  end
+
+  context 'with duplicate product' do
+    before(:each) do
+      @book1 = mock_model(Product, :price => 2)
+      @cart = Cart.new
+      @cart.add_product @book1
+      @cart.add_product @book1
+    end
+    it 'should contain one item in cart but report two' do
+      @cart.items.size.should == 1
+      @cart.total_items.should == 2
+    end
+    it 'should report price x quantity for item in cart' do
+      @cart.total_price.should == 4
+    end
+  end
+
+end