add missing spec for Server.build_from_bson method

devops-service/spec/models/server_spec.rb

@@ -44,6 +44,14 @@ RSpec.describe Devops::Model::Server, type: :model do
     end
   end
 
+  describe '.build_from_bson' do
+    it 'takes a hash and returns instance of Server model' do
+      model = described_class.build_from_bson('id' => 'foo')
+      expect(model).to be_an_instance_of(described_class)
+      expect(model.id).to eq 'foo'
+    end
+  end
+
   it '#to_hash_without_id returns not nil fields' do
     server = described_class.new('run_list' => [], 'project' =>  'asd')
     expect(server.to_hash_without_id.keys).to match_array(%w(run_list project))