use expect instead of should in specs

spec/models/article_spec.rb

@@ -6,39 +6,39 @@ describe Article do
 
   it 'has a unique name' do
     article2 = FactoryGirl.build :article, supplier: supplier, name: article.name
-    article2.should_not be_valid
+    expect(article2).to be_invalid
   end
 
   it 'computes the gross price correctly' do
     article.deposit = 0
     article.tax = 12
-    article.gross_price.should == (article.price * 1.12).round(2)
+    expect(article.gross_price).to eq((article.price * 1.12).round(2))
     article.deposit = 1.20
-    article.gross_price.should == ((article.price + 1.20) * 1.12).round(2)
+    expect(article.gross_price).to eq(((article.price + 1.20) * 1.12).round(2))
   end
 
   it 'gross price >= net price' do
-    article.gross_price.should >= article.price
+    expect(article.gross_price).to be >= article.price
   end
 
   it 'fc-price > gross price' do
-    article.fc_price.should > article.gross_price
+    expect(article.fc_price).to be > article.gross_price
   end
 
   it 'knows when it is deleted' do
-    supplier.deleted?.should be_false
+    expect(supplier.deleted?).to be_false
     supplier.mark_as_deleted
-    supplier.deleted?.should be_true
+    expect(supplier.deleted?).to be_true
   end
 
   it 'keeps a price history' do
-    article.article_prices.count.should == 1
+    expect(article.article_prices.count).to eq(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
+    expect(article.article_prices.count).to eq(2)
+    expect(article.article_prices[0].price).to eq(article.price)
+    expect(article.article_prices[-1].price).to eq(oldprice)
   end
 
 end