public SettingsMemoryPersistenceTest()
        {
            _persistence = new SettingsMemoryPersistence();

            _persistence.OpenAsync(null).Wait();
            _persistence.ClearAsync(null).Wait();

            _fixture = new SettingsPersistenceFixture(_persistence);
        }
        public SettingsMongoDbPersistenceTest()
        {
            var MONGODB_COLLECTION  = Environment.GetEnvironmentVariable("MONGODB_COLLECTION") ?? "test_settings";
            var MONGODB_SERVICE_URI = Environment.GetEnvironmentVariable("MONGODB_SERVICE_URI") ?? "mongodb://localhost:27017/test";

            var config = ConfigParams.FromTuples(
                "collection", MONGODB_COLLECTION,
                "connection.uri", MONGODB_SERVICE_URI
                );

            _persistence = new SettingsMongoDbPersistence();
            _persistence.Configure(config);
            _persistence.OpenAsync(null).Wait();
            _persistence.ClearAsync(null).Wait();

            _fixture = new SettingsPersistenceFixture(_persistence);
        }