Add currency parameter to #coin method

lib/coinmarketcap.rb

@@ -12,8 +12,8 @@ def self.coins(limit = nil)
     end
   end
 
-  def self.coin(id)
-    HTTParty.get("https://api.coinmarketcap.com/v1/ticker/#{id}/")
+  def self.coin(id, currency = 'USD')
+    HTTParty.get("https://api.coinmarketcap.com/v1/ticker/#{id}/?convert=#{currency}")
   end
 
   def self.global(currency = 'USD')

spec/coinmarketcap_spec.rb

@@ -64,6 +64,18 @@
         end
       end
     end
+
+    context 'with valid id and a currency code' do
+      it "should receive a 200 response with coin details" do
+        VCR.use_cassette('single_eur_coin_response') do
+          response = Coinmarketcap.coin('bitcoin', 'EUR')
+          coin = JSON.parse(response.body)
+          expect(response.code).to eq(200)
+          expect(coin.count).to eq(1)
+          expect(coin.first['market_cap_eur'].to_i).to be > 0
+        end
+      end
+    end
   end
 
   describe "#global" do