Add "servers" support to Ruby API client (#1280)

* update ruby samples with OAS3 spec

* add server support to ruby api client

* minor format change

* minor format fix, skip form models

* better exception and add test for invaid value

* remove exception test code

samples/client/petstore/ruby/spec/configuration_spec.rb

@@ -22,4 +22,34 @@ describe Petstore::Configuration do
       end
     end
   end
+
+  describe 'server settings' do
+    it 'should return an array of server settings' do
+      expect(config.auth_settings).not_to be_empty
+    end
+
+    it 'should get the first url' do
+      url = config.server_url(0, server: "dev-petstore", port: "8080")
+      expect(url).to eq("http://dev-petstore.swagger.io:8080/v2")
+    end
+
+    it 'should get the first url with default values' do
+      url = config.server_url(0)
+      expect(url).to eq("http://petstore.swagger.io:80/v2")
+    end
+
+    it 'should get the second url with default values' do
+      url = config.server_url(1)
+      expect(url).to eq("https://api.gigantic-server.com:8080/v2")
+    end
+
+    it 'should get the second url' do
+      url = config.server_url(1, version: "v1")
+      expect(url).to eq("https://api.gigantic-server.com:8080/v1")
+    end
+
+    it 'should raise error due to invalid enum value' do
+      expect{config.server_url(1, version: "v6")}.to raise_error(ArgumentError)
+    end
+  end
 end