add some rspec tests for supplier and article

spec/models/article_spec.rb

@@ -0,0 +1,44 @@
+require 'spec_helper'
+
+describe Article do
+  let(:supplier) { FactoryGirl.create :supplier }
+  let(:article) { FactoryGirl.create :article, supplier: supplier }
+
+  it 'has a unique name' do
+    article2 = FactoryGirl.build :article, supplier: supplier, name: article.name
+    article2.should_not be_valid
+  end
+
+  it 'computes the gross price correctly' do
+    article.deposit = 0
+    article.tax = 12
+    article.gross_price.should == (article.price * 1.12).round(2)
+    article.deposit = 1.20
+    article.gross_price.should == ((article.price + 1.20) * 1.12).round(2)
+  end
+
+  it 'gross price >= net price' do
+    article.gross_price.should >= article.price
+  end
+
+  it 'fc-price > gross price' do
+    article.fc_price.should > article.gross_price
+  end
+
+  it 'knows when it is deleted' do
+    supplier.deleted?.should be_false
+    supplier.mark_as_deleted
+    supplier.deleted?.should be_true
+  end
+
+  it 'keeps a price history' do
+    article.article_prices.count.should == 1
+    oldprice = article.price
+    article.price += 1
+    article.save!
+    article.article_prices.count.should == 2
+    article.article_prices[0].price.should == article.price
+    article.article_prices[-1].price.should == oldprice
+  end
+
+end